Apparatus and method for sending and receiving broadcast signals

ABSTRACT

A broadcast signal transmitter is disclosed. A broadcast signal transmitter according to the present invention comprises an input formatting module configured to de-multiplex an input stream into at least one PLP (Physical Layer Pipe); a BICM (Bit Interleaved Coded Modulation) module configured to perform error correction processing on the data of the least one PLP; a frame building module configured to generate a signal frame including the at least one PLP; a waveform generating module configured to generate the broadcast signal by inserting a preamble into the signal frame and performing OFDM modulation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application No.62/137,800 filed on 24 Mar. 2015 in U.S. Provisional Application No.62/152,050 filed on 24 Apr. 2015 in U.S. Provisional Application No.62/145,456 filed on 9 Apr. 2015 in U.S. Provisional Application No.62/138,962 filed on 26 Mar. 2015 in US, and Provisional Application No.62/142,487 filed on 3 Apr. 2015 in US, the entire contents of which ishereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

2. Discussion of the Related Art

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus and methodfor transmitting broadcast signals to multiplex data of a broadcasttransmission/reception system providing two or more different broadcastservices in a time domain and transmit the multiplexed data through thesame RF signal bandwidth and an apparatus and method for receivingbroadcast signals corresponding thereto.

Another object of the present invention is to provide an apparatus fortransmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals toclassify data corresponding to services by components, transmit datacorresponding to each component as a data pipe, receive and process thedata

Still another object of the present invention is to provide an apparatusfor transmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals tosignal signaling information necessary to provide broadcast signals.

To solve the technical problems above, a broadcast signal transmitteraccording to one embodiment of the present invention comprises an inputformatting module configured to de-multiplex an input stream into atleast one PLP (Physical Layer Pipe); a BICM (Bit Interleaved CodedModulation) module configured to perform error correction processing onthe data of the least one PLP; a frame building module configured togenerate a signal frame including the at least one PLP; a waveformgenerating module configured to generate the broadcast signal byinserting a preamble into the signal frame and performing OFDMmodulation, wherein the waveform generating module further comprises apilot insertion module configured to insert pilots including CPs(Continual Pilots) and SPs (Scattered Pilots) to the broadcast signaland the CPs are inserted in every symbol of the signal frame and thenumber of the CPs is determined based on FFT (Fast Fourier Transform)size.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the number of carriers included in the signal frameis reduced by a unit from a maximum number of carriers, the unit beingobtained by multiplying a control unit value by a reducing coefficient,and the control unit value corresponds to the predetermined number ofcarriers which are determined based on the FFT size.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the control unit value corresponds to 96 when the FFTsize is 8, 192 when the FFT size is 16 and 384 when the FFT size is 32.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the CPs include a common CP set and an additional CPset.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the common CP set includes a first CP set for 32K FFTmode, a second CP set for 16K FFT mode, and a third CP set for 8K FFTmode; and the first CP set, the second CP set, and the third CP set aregenerated by using a predetermined first reference CP set.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the first CP set is generated by adding a secondreference CP set to the first reference CP set and the second referenceCP set is generated by reversing and shifting the first reference CPset.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the second CP set is generated by deriving CPs ofevery second index from CPs included in the first CP set.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the third CP set is generated by deriving CPs ofevery fourth index from CPs included in the first CP set.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the additional CP set is added at carrier locationsSP for ensuring a constant number of data carriers in every data symbolof the signal frame, and the additional CP set depends on SP pattern andthe FFT size.

In a broadcast signal transmitter according to one embodiment of thepresent invention, the number of carriers included in the signal frameis reduced by a unit from a maximum number of carriers, the unit beingobtained by multiplying a control unit value by a reducing coefficient,and the control unit value corresponds to a predetermined number ofcarriers which are determined based on the FFT size, wherein theadditional CP set for a specific SP pattern and a specific FFT size isadded differently according to the reducing coefficient.

A method for transmitting a broadcast signal of a broadcast signaltransmitter according to one embodiment of the present inventioncomprises demultiplexing an input stream into at least one PLP (PhysicalLayer Pipe); performing error correction processing on the data of theleast one PLP; generating a signal frame including the at least one PLP;and generating a broadcast signal by inserting a preamble into thesignal frame and performing OFDM modulation, wherein the generating asignal frame further comprises inserting pilots including CPs (ContinualPilots) and SPs (Scattered Pilots) to the broadcast signal, the CPs areinserted in every symbol of the signal frame, and the number of the CPsis determined based on FFT (Fast Fourier Transform) size.

The present invention can process data according to servicecharacteristics to control QoS (Quality of Services) for each service orservice component, thereby providing various broadcast services.

The present invention can achieve transmission flexibility bytransmitting various broadcast services through the same RF signalbandwidth.

The present invention can improve data transmission efficiency andincrease robustness of transmission/reception of broadcast signals usinga MIMO system.

According to the present invention, it is possible to provide broadcastsignal transmission and reception methods and apparatus capable ofreceiving digital broadcast signals without error even with mobilereception equipment or in an indoor environment.

Further aspects and effects of the present invention will be describedmore detail with embodiments in belows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

FIG. 26 illustrates a basic operation of a twisted row-column blockinterleaver according to an exemplary embodiment of the presentinvention.

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another exemplary embodiment of the presentinvention.

FIG. 28 illustrates a diagonal reading pattern of the twisted row-columnblock interleaver according to the exemplary embodiment of the presentinvention.

FIG. 29 illustrates XFECBLOCK interleaved from each interleaving arrayaccording to an exemplary embodiment of the present invention.

FIG. 30 illustrates a block diagram of a synchronization & demodulationmodule of a broadcast signal receiver in detail according to oneembodiment of the present invention.

FIGS. 31 to 33 illustrate embodiments of a flexible NoC structure of abroadcast signal according to the present invention.

FIGS. 34 to 37 illustrate cases according to one embodiment of thepresent invention, where constraints are generated to maintain aconstant NoA when NoC is changed according to FFT size.

FIG. 38 illustrates a method for generating CP indices according to oneembodiment of the present invention.

FIG. 39 illustrates a method for generating a CP set according to FFTsize according to an embodiment of the present invention.

FIGS. 40 and 41 illustrate a method for generating a reference CP setand generating a CP pattern using the reference CP set according to oneembodiment of the present invention.

FIGS. 42 to 45 illustrate a method for generating a reference CP set andgenerating a CP pattern using the reference CP set according to anotherone embodiment of the present invention.

FIGS. 46 to 51 illustrate performance and distribution of CP sets shownin FIGS. 42 to 45.

FIG. 52 illustrates additional CP sets according to an embodiment of thepresent invention.

FIG. 53 illustrates a method for positioning the index of an additionalCP set of FIG. 52.

FIG. 54 illustrates a method for transmitting a broadcast signal ofanother broadcast signal transmitter according to an embodiment of thepresent invention.

FIG. 55 illustrates a method for receiving a broadcast signal accordingto one embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings. Also, the term blockand module are used similarly to indicate logical/functional unit ofparticular signal/data processing.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

The present invention may defines three physical layer (PL)profiles—base, handheld and advanced profiles—each optimized to minimizereceiver complexity while attaining the performance required for aparticular use case. The physical layer (PHY) profiles are subsets ofall configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differslightly in specific blocks and/or parameters. Additional PHY profilescan be defined in the future. For the system evolution, future profilescan also be multiplexed with the existing profiles in a single RFchannel through a future extension frame (FEF). The details of each PHYprofile are described below.

1. Base profile

The base profile represents a main use case for fixed receiving devicesthat are usually connected to a roof-top antenna. The base profile alsoincludes portable devices that could be transported to a place butbelong to a relatively stationary reception category. Use of the baseprofile could be extended to handheld devices or even vehicular by someimproved implementations, but those use cases are not expected for thebase profile receiver operation.

Target SNR range of reception is from approximately 10 to 20 dB, whichincludes the 15 dB SNR reception capability of the existing broadcastsystem (e.g. ATSC A/53). The receiver complexity and power consumptionis not as critical as in the battery-operated handheld devices, whichwill use the handheld profile. Key system parameters for the baseprofile are listed in below table 1.

TABLE 1 LDPC codeword length 16K, 64K bits Constellation size 4~10 bpcu(bits per channel use) Time de-interleaving memory size ≦2¹⁹ data cellsPilot patterns Pilot pattern for fixed reception FFT size 16K, 32Kpoints

2. Handheld Profile

The handheld profile is designed for use in handheld and vehiculardevices that operate with battery power. The devices can be moving withpedestrian or vehicle speed. The power consumption as well as thereceiver complexity is very important for the implementation of thedevices of the handheld profile. The target SNR range of the handheldprofile is approximately 0 to 10 dB, but can be configured to reachbelow 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effectcaused by receiver mobility is the most important performance attributeof the handheld profile. Key system parameters for the handheld profileare listed in the below table 2.

TABLE 2 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory size ≦2¹⁸ data cells Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

3. Advanced Profile

The advanced profile provides highest channel capacity at the cost ofmore implementation complexity. This profile requires using MIMOtransmission and reception, and UHDTV service is a target use case forwhich this profile is specifically designed. The increased capacity canalso be used to allow an increased number of services in a givenbandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30dB. MIMO transmission may initially use existing elliptically-polarizedtransmission equipment, with extension to full-power cross-polarizedtransmission in the future. Key system parameters for the advancedprofile are listed in below table 3.

TABLE 3 LDPC codeword length 16K, 64K bits Constellation size 8~12 bpcuTime de-interleaving memory size ≦2¹⁹ data cells Pilot patterns Pilotpattern for fixed reception FFT size 16K, 32K points

In this case, the base profile can be used as a profile for both theterrestrial broadcast service and the mobile broadcast service. That is,the base profile can be used to define a concept of a profile whichincludes the mobile profile. Also, the advanced profile can be dividedadvanced profile for a base profile with MIMO and advanced profile for ahandheld profile with MIMO. Moreover, the three profiles can be changedaccording to intention of the designer.

The following terms and definitions may apply to the present invention.The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefinedmodulation and coding, which may be used for future extensions or asrequired by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of Kbch bits which form the input toone FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDMtransmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encodedblocks of PLS2 data

data pipe: logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s).

data pipe unit: a basic unit for allocating data cells to a DP in aframe.

data symbol: OFDM symbol in a frame which is not a preamble symbol (theframe signaling symbol and frame edge symbol is included in the datasymbol)

DP_ID: this 8-bit field identifies uniquely a DP within the systemidentified by the SYSTEM_ID

dummy cell: cell carrying a pseudo-random value used to fill theremaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS informationdata

frame: physical layer time slot that starts with a preamble and endswith a frame edge symbol

frame repetition unit: a set of frames belonging to same or differentphysical layer profile including a FEF, which is repeated eight times ina super-frame

fast information channel: a logical channel in a frame that carries themapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to theactive symbol period Ts expressed in cycles of the elementary period T

frame signaling symbol: OFDM symbol with higher pilot density used atthe start of a frame in certain combinations of FFT size, guard intervaland scattered pilot (sp) pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the endof a frame in certain combinations of FFT size, guard interval andscattered pilot pattern

frame-group: the set of all the frames having the same PHY profile typein a super-frame.

future extension frame: physical layer time slot within the super-framethat could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, ofwhich the input is one or more MPEG2-TS or IP or general stream(s) andof which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered tothe end users by the system.

normal data symbol: data symbol excluding the frame signaling symbol andthe frame edge symbol

PHY profile: subset of all configurations that a corresponding receivershould implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1: a first set of PLS data carried in the FSS symbols having a fixedsize, coding and modulation, which carries basic information about thesystem as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, whichcarries more detailed PLS data about the system and the DPs

PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame

PLS2 static data: PLS2 data that remains static for the duration of aframe-group

preamble signaling data: signaling data carried by the preamble symboland used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS dataand is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan todetect the system signal, its timing, frequency offset, and FFT-size.

reserved for future use: not defined by the present document but may bedefined in future

super-frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which timeinterleaving is carried out, corresponding to one use of the timeinterleaver memory

TI group: unit over which dynamic capacity allocation for a particularDP is carried out, made up of an integer, dynamically varying number ofXFECBLOCKs

NOTE: The TI group may be mapped directly to one frame or may be mappedto multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDMfashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDMfashion

XFECBLOCK: set of Ncells cells carrying all the bits of one LDPCFECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting block 1000, a BICM (Bit interleaved coding &modulation) block 1010, a frame structure block 1020, an OFDM(Orthogonal Frequency Division Multiplexing) generation block 1030 and asignaling generation block 1040. A description will be given of theoperation of each module of the apparatus for transmitting broadcastsignals.

IP stream/packets and MPEG2-TS are the main input formats, other streamtypes are handled as General Streams. In addition to these data inputs,Management Information is input to control the scheduling and allocationof the corresponding bandwidth for each input stream. One or multiple TSstream(s), IP stream(s) and/or General Stream(s) inputs aresimultaneously allowed.

The input formatting block 1000 can demultiplex each input stream intoone or multiple data pipe(s), to each of which an independent coding andmodulation is applied. The data pipe (DP) is the basic unit forrobustness control, thereby affecting quality-of-service (QoS). One ormultiple service(s) or service component(s) can be carried by a singleDP. Details of operations of the input formatting block 1000 will bedescribed later.

The data pipe is a logical channel in the physical layer that carriesservice data or related metadata, which may carry one or multipleservice(s) or service component(s).

Also, the data pipe unit: a basic unit for allocating data cells to a DPin a frame.

In the BICM block 1010, parity data is added for error correction andthe encoded bit streams are mapped to complex-value constellationsymbols. The symbols are interleaved across a specific interleavingdepth that is used for the corresponding DP. For the advanced profile,MIMO encoding is performed in the BICM block 1010 and the additionaldata path is added at the output for MIMO transmission. Details ofoperations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPsinto the OFDM symbols within a frame. After mapping, the frequencyinterleaving is used for frequency-domain diversity, especially tocombat frequency-selective fading channels. Details of operations of theFrame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDMGeneration block 1030 can apply conventional OFDM modulation having acyclic prefix as guard interval. For antenna space diversity, adistributed MISO scheme is applied across the transmitters. In addition,a Peak-to-Average Power Reduction (PAPR) scheme is performed in the timedomain. For flexible network planning, this proposal provides a set ofvarious FFT sizes, guard interval lengths and corresponding pilotpatterns. Details of operations of the OFDM Generation block 1030 willbe described later.

The Signaling Generation block 1040 can create physical layer signalinginformation used for the operation of each functional block. Thissignaling information is also transmitted so that the services ofinterest are properly recovered at the receiver side. Details ofoperations of the Signaling Generation block 1040 will be describedlater.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according toembodiments of the present invention. A description will be given ofeach figure.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention. FIG. 2 shows an input formatting module whenthe input signal is a single input stream.

The input formatting block illustrated in FIG. 2 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

The input to the physical layer may be composed of one or multiple datastreams. Each data stream is carried by one DP. The mode adaptationmodules slice the incoming data stream into data fields of the basebandframe (BBF). The system supports three types of input data streams:MPEG2-TS, Internet protocol (IP) and Generic stream (GS). MPEG2-TS ischaracterized by fixed length (188 byte) packets with the first bytebeing a sync-byte (0x47). An IP stream is composed of variable length IPdatagram packets, as signaled within IP packet headers. The systemsupports both IPv4 and IPv6 for the IP stream. GS may be composed ofvariable length packets or constant length packets, signaled withinencapsulation packet headers.

(a) shows a mode adaptation block 2000 and a stream adaptation 2010 forsignal DP and (b) shows a PLS generation block 2020 and a PLS scrambler2030 for generating and processing PLS data. A description will be givenof the operation of each block.

The Input Stream Splitter splits the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams. Themode adaptation module 2010 is comprised of a CRC Encoder, BB (baseband)Frame Slicer, and BB Frame Header Insertion block.

The CRC Encoder provides three kinds of CRC encoding for error detectionat the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. Thecomputed CRC bytes are appended after the UP. CRC-8 is used for TSstream and CRC-32 for IP stream. If the GS stream doesn't provide theCRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. Thefirst received bit is defined to be the MSB. The BB Frame Slicerallocates a number of input bits equal to the available data fieldcapacity. To allocate a number of input bits equal to the BBF payload,the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2bytes is inserted in front of the BB Frame. The BBF header is composedof STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to thefixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes)at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block andBB scrambler.

The stuffing insertion block can insert stuffing field into a payload ofa BB frame. If the input data to the stream adaptation is sufficient tofill a BB-Frame, STUFFI is set to ‘0’ and the BBF has no stuffing field.Otherwise STUFFI is set to ‘1’ and the stuffing field is insertedimmediately after the BBF header. The stuffing field comprises two bytesof the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. Thescrambling sequence is synchronous with the BBF. The scrambling sequenceis generated by the feed-back shift register.

The PLS generation block 2020 can generate physical layer signaling(PLS) data. The PLS provides the receiver with a means to accessphysical layer DPs. The PLS data consists of PLS1 data and PLS2 data.

The PLS1 data is a first set of PLS data carried in the FSS symbols inthe frame having a fixed size, coding and modulation, which carriesbasic information about the system as well as the parameters needed todecode the PLS2 data. The PLS1 data provides basic transmissionparameters including parameters required to enable the reception anddecoding of the PLS2 data. Also, the PLS1 data remains constant for theduration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol,which carries more detailed PLS data about the system and the DPs. ThePLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data thatremains static for the duration of a frame-group and the PLS2 dynamicdata is PLS2 data that may dynamically change frame-by-frame.

Details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energydispersal.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 3 shows a mode adaptation block of the input formatting block whenthe input signal corresponds to multiple input streams.

The mode adaptation block of the input formatting block for processingthe multiple input streams can independently process the multiple inputstreams.

Referring to FIG. 3, the mode adaptation block for respectivelyprocessing the multiple input streams can include an input streamsplitter 3000, an input stream synchronizer 3010, a compensating delayblock 3020, a null packet deletion block 3030, a head compression block3040, a CRC encoder 3050, a BB frame slicer 3060 and a BB headerinsertion block 3070. Description will be given of each block of themode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB headerinsertion block 3070 correspond to those of the CRC encoder, BB frameslicer and BB header insertion block described with reference to FIG. 2and thus description thereof is omitted.

The input stream splitter 3000 can split the input TS, IP, GS streamsinto multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The ISSY canprovide suitable means to guarantee Constant Bit Rate (CBR) and constantend-to-end transmission delay for any input data format. The ISSY isalways used for the case of multiple DPs carrying TS, and optionallyused for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet streamfollowing the insertion of ISSY information to allow a TS packetrecombining mechanism without requiring additional memory in thereceiver.

The null packet deletion block 3030, is used only for the TS inputstream case. Some TS input streams or split TS streams may have a largenumber of null-packets present in order to accommodate VBR (variablebit-rate) services in a CBR TS stream. In this case, in order to avoidunnecessary transmission overhead, null-packets can be identified andnot transmitted. In the receiver, removed null-packets can bere-inserted in the exact place where they were originally by referenceto a deleted null-packet (DNP) counter that is inserted in thetransmission, thus guaranteeing constant bit-rate and avoiding the needfor time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression toincrease transmission efficiency for TS or IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about thesync-byte configuration (0x47) and the packet length (188 Byte). If theinput TS stream carries content that has only one PID, i.e., for onlyone service component (video, audio, etc.) or service sub-component (SVCbase layer, SVC enhancement layer, MVC base view or MVC dependentviews), TS packet header compression can be applied (optionally) to theTransport Stream. IP packet header compression is used optionally if theinput steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 4 illustrates a stream adaptation block of the input formattingmodule when the input signal corresponds to multiple input streams.

Referring to FIG. 4, the mode adaptation block for respectivelyprocessing the multiple input streams can include a scheduler 4000, an1-Frame delay block 4010, a stuffing insertion block 4020, an in-bandsignaling 4030, a BB Frame scrambler 4040, a PLS generation block 4050and a PLS scrambler 4060. Description will be given of each block of thestream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler4040, the PLS generation block 4050 and the PLS scrambler 4060correspond to those of the stuffing insertion block, BB scrambler, PLSgeneration block and the PLS scrambler described with reference to FIG.2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across theentire frame from the amount of FECBLOCKs of each DP. Including theallocation for PLS, EAC and FIC, the scheduler generate the values ofPLS2-DYN data, which is transmitted as in-band signaling or PLS cell inFSS of the frame. Details of FECBLOCK, EAC and FIC will be describedlater.

The 1-Frame delay block 4010 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 datainto a DP of a frame.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to an embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the a BICM block according to anembodiment of the present invention can independently process DPs inputthereto by independently applying SISO, MISO and MIMO schemes to thedata pipes respectively corresponding to data paths. Consequently, theapparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can controlQoS for each service or service component transmitted through each DP.

(a) shows the BICM block shared by the base profile and the handheldprofile and (b) shows the BICM block of the advanced profile.

The BICM block shared by the base profile and the handheld profile andthe BICM block of the advanced profile can include plural processingblocks for processing each DP.

A description will be given of each processing block of the BICM blockfor the base profile and the handheld profile and the BICM block for theadvanced profile.

A processing block 5000 of the BICM block for the base profile and thehandheld profile can include a Data FEC encoder 5010, a bit interleaver5020, a constellation mapper 5030, an SSD (Signal Space Diversity)encoding block 5040 and a time interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBFto generate FECBLOCK procedure using outer coding (BCH), and innercoding (LDPC). The outer coding (BCH) is optional coding method. Detailsof operations of the Data FEC encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder5010 to achieve optimized performance with combination of the LDPC codesand modulation scheme while providing an efficiently implementablestructure. Details of operations of the bit interleaver 5020 will bedescribed later.

The constellation mapper 5030 can modulate each cell word from the bitinterleaver 5020 in the base and the handheld profiles, or cell wordfrom the Cell-word demultiplexer 5010-1 in the advanced profile usingeither QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) ornon-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give apower-normalized constellation point, el. This constellation mapping isapplied only for DPs. Observe that QAM-16 and NUQs are square shaped,while NUCs have arbitrary shape. When each constellation is rotated byany multiple of 90 degrees, the rotated constellation exactly overlapswith its original one. This “rotation-sense” symmetric property makesthe capacities and the average powers of the real and imaginarycomponents equal to each other. Both NUQs and NUCs are definedspecifically for each code rate and the particular one used is signaledby the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D),and four (4D) dimensions to increase the reception robustness underdifficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parametersof time interleaving (TI) may be set differently for each DP. Details ofoperations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile caninclude the Data FEC encoder, bit interleaver, constellation mapper, andtime interleaver. However, the processing block 5000-1 is distinguishedfrom the processing block 5000 further includes a cell-worddemultiplexer 5010-1 and a MIMO encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver,constellation mapper, and time interleaver in the processing block5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver5020, constellation mapper 5030, and time interleaver 5050 described andthus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advancedprofile to divide the single cell-word stream into dual cell-wordstreams for MIMO processing. Details of operations of the cell-worddemultiplexer 5010-1 will be described later.

The MIMO encoding block 5020-1 can processing the output of thecell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMOencoding scheme was optimized for broadcasting signal transmission. TheMIMO technology is a promising way to get a capacity increase but itdepends on channel characteristics. Especially for broadcasting, thestrong LOS component of the channel or a difference in the receivedsignal power between two antennas caused by different signal propagationcharacteristics makes it difficult to get capacity gain from MIMO. Theproposed MIMO encoding scheme overcomes this problem using arotation-based pre-coding and phase randomization of one of the MIMOoutput signals.

MIMO encoding is intended for a 2×2 MIMO system requiring at least twoantennas at both the transmitter and the receiver. Two MIMO encodingmodes are defined in this proposal; full-rate spatial multiplexing(FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). TheFR-SM encoding provides capacity increase with relatively smallcomplexity increase at the receiver side while the FRFD-SM encodingprovides capacity increase and additional diversity gain with a greatcomplexity increase at the receiver side. The proposed MIMO encodingscheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which meansall DPs in the advanced profile frame are processed by the MIMO encoder.MIMO processing is applied at DP level. Pairs of the ConstellationMapper outputs NUQ (e1,i and e2,i) are fed to the input of the MIMOEncoder. Paired MIMO Encoder output (g1,i and g2,i) is transmitted bythe same carrier k and OFDM symbol l of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layersignaling (PLS), emergency alert channel (EAC) and fast informationchannel (FIC). EAC is a part of a frame that carries EAS informationdata and FIC is a logical channel in a frame that carries the mappinginformation between a service and the corresponding base DP. Details ofthe EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FICcan include a PLS FEC encoder 6000, a bit interleaver 6010, aconstellation mapper 6020 and time interleaver 6030.

Also, the PLS FEC encoder 6000 can include a scrambler, BCHencoding/zero insertion block, LDPC encoding block and LDPC paritypunturing block. Description will be given of each block of the BICMblock.

The PLS FEC encoder 6000 can encode the scrambled PLS 1/2 data, EAC andFIC section.

The scrambler can scramble PLS1 data and PLS2 data before BCH encodingand shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on thescrambled PLS1/2 data using the shortened BCH code for PLS protectionand insert zero bits after the BCH encoding. For PLS1 data only, theoutput bits of the zero insertion may be permutted before LDPC encoding.

The LDPC encoding block can encode the output of the BCH encoding/zeroinsertion block using LDPC code. To generate a complete coded block,Cldpc, parity bits, Pldpc are encoded systematically from eachzero-inserted PLS information block, Ildpc and appended after it.

C _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . i _(K) _(ldpc) ⁻¹ ,p₀ ,p ₁ ,p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹]  [Equation 1]

The LDPC code parameters for PLS1 and PLS2 are as following table 4.

TABLE 4 Signaling Kldpc code Type Ksig Kbch Nbch_parity (=Nbch) NldpcNldpc_parity rate Qldpc PLS1 342 1020 60 1080 4320 3240 1/4  36 PLS2<1021 >1020 2100 2160 7200 5040 3/10 56

The LDPC parity punturing block can perform puncturing on the PLS1 dataand PLS2 data.

When shortening is applied to the PLS1 data protection, some LDPC paritybits are punctured after LDPC encoding. Also, for the PLS2 dataprotection, the LDPC parity bits of PLS2 are punctured after LDPCencoding. These punctured bits are not transmitted.

The bit interleaver 6010 can interleave the each shortened and puncturedPLS1 data and PLS2 data. The constellation mapper 6020 can map the bitinterleaved PLS1 data and PLS2 data onto constellations.

The time interleaver 6030 can interleave the mapped PLS1 data and PLS2data.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

The frame building block illustrated in FIG. 7 corresponds to anembodiment of the frame building block 1020 described with reference toFIG. 1.

Referring to FIG. 7, the frame building block can include a delaycompensation block 7000, a cell mapper 7010 and a frequency interleaver7020. Description will be given of each block of the frame buildingblock.

The delay compensation block 7000 can adjust the timing between the datapipes and the corresponding PLS data to ensure that they are co-timed atthe transmitter end. The PLS data is delayed by the same amount as datapipes are by addressing the delays of data pipes caused by the InputFormatting block and BICM block. The delay of the BICM block is mainlydue to the time interleaver 5050. In-band signaling data carriesinformation of the next TI group so that they are carried one frameahead of the DPs to be signaled. The Delay Compensating block delaysin-band signaling data accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams anddummy cells into the active carriers of the OFDM symbols in the frame.The basic function of the cell mapper 7010 is to map data cells producedby the TIs for each of the DPs, PLS cells, and EAC/FIC cells, if any,into arrays of active OFDM cells corresponding to each of the OFDMsymbols within a frame. Service signaling data (such as PSI (programspecific information)/SI) can be separately gathered and sent by a datapipe. The Cell Mapper operates according to the dynamic informationproduced by the scheduler and the configuration of the frame structure.Details of the frame will be described later.

The frequency interleaver 7020 can randomly interleave data cellsreceived from the cell mapper 7010 to provide frequency diversity. Also,the frequency interleaver 7020 can operate on very OFDM symbol paircomprised of two sequential OFDM symbols using a differentinterleaving-seed order to get maximum interleaving gain in a singleframe. Details of operations of the frequency interleaver 7020 will bedescribed later.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 8 illustrates an OFMD generation block according to an embodimentof the present invention.

The OFMD generation block illustrated in FIG. 8 corresponds to anembodiment of the OFMD generation block 1030 described with reference toFIG. 1.

The OFDM generation block modulates the OFDM carriers by the cellsproduced by the Frame Building block, inserts the pilots, and producesthe time domain signal for transmission. Also, this block subsequentlyinserts guard intervals, and applies PAPR (Peak-to-Average Power Radio)reduction processing to produce the final RF signal.

Referring to FIG. 8, the frame building block can include a pilot andreserved tone insertion block 8000, a 2D-eSFN encoding block 8010, anIFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block8030, a guard interval insertion block 8040, a preamble insertion block8050, other system insertion block 8060 and a DAC block 8070.Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots andthe reserved tone.

Various cells within the OFDM symbol are modulated with referenceinformation, known as pilots, which have transmitted values known apriori in the receiver. The information of pilot cells is made up ofscattered pilots (SP), continual pilots (CP), edge pilots (EP), FSS(frame signaling symbol) pilots and FES (frame edge symbol) pilots. Eachpilot is transmitted at a particular boosted power level according topilot type and pilot pattern. The value of the pilot information isderived from a reference sequence, which is a series of values, one foreach transmitted carrier on any given symbol. The pilots can be used forframe synchronization, frequency synchronization, time synchronization,channel estimation, and transmission mode identification, and also canbe used to follow the phase noise.

Reference information, taken from the reference sequence, is transmittedin scattered pilot cells in every symbol except the preamble, FSS andFES of the frame. Continual pilots are inserted in every symbol of theframe. The number and location of continual pilots depends on both theFFT size and the scattered pilot pattern. The edge carriers are edgepilots in every symbol except for the preamble symbol. They are insertedin order to allow frequency interpolation up to the edge of thespectrum. FSS pilots are inserted in FSS(s) and FES pilots are insertedin FES. They are inserted in order to allow time interpolation up to theedge of the frame.

The system according to an embodiment of the present invention supportsthe SFN network, where distributed MISO scheme is optionally used tosupport very robust transmission mode. The 2D-eSFN is a distributed MISOscheme that uses multiple TX antennas, each of which is located in thedifferent transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing todistorts the phase of the signals transmitted from multipletransmitters, in order to create both time and frequency diversity inthe SFN configuration. Hence, burst errors due to low flat fading ordeep-fading for a long time can be mitigated.

The IFFT block 8020 can modulate the output from the 2D-eSFN encodingblock 8010 using OFDM modulation scheme. Any cell in the data symbolswhich has not been designated as a pilot (or as a reserved tone) carriesone of the data cells from the frequency interleaver. The cells aremapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on inputsignal using various PAPR reduction algorithm in the time domain.

The guard interval insertion block 8040 can insert guard intervals andthe preamble insertion block 8050 can insert preamble in front of thesignal. Details of a structure of the preamble will be described later.The other system insertion block 8060 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 8070 can convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through multiple output antennas accordingto the physical layer profiles. A Tx antenna according to an embodimentof the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention can includea synchronization & demodulation module 9000, a frame parsing module9010, a demapping & decoding module 9020, an output processor 9030 and asignaling decoding module 9040. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and perform demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 9010 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 9010 can perform deinterleaving corresponding to areverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 9400 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 9020 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 9200 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 9020 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 9040.

The output processor 9030 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 9030 can acquirenecessary control information from data output from the signalingdecoding module 9040. The output of the output processor 9030corresponds to a signal input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 9040 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 9000. Asdescribed above, the frame parsing module 9010, demapping & decodingmodule 9020 and output processor 9030 can execute functions thereofusing the data output from the signaling decoding module 9040.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 10 shows an example configuration of the frame types and FRUs in asuper-frame. (a) shows a super frame according to an embodiment of thepresent invention, (b) shows FRU (Frame Repetition Unit) according to anembodiment of the present invention, (c) shows frames of variable PHYprofiles in the FRU and (d) shows a structure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM of the frames, and is repeated eight times ina super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in (d), the frame comprises a preamble, one or moreframe signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. The detaileddescription of the preamble will be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has more dense pilot pattern than the normal data symbol.The FES has exactly the same pilots as the FSS, which enablesfrequency-only interpolation within the FES and temporal interpolation,without extrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is splitinto three main parts: the preamble signaling data 11000, the PLS1 data11010 and the PLS2 data 11020. The purpose of the preamble, which iscarried by the preamble symbol in every frame, is to indicate thetransmission type and basic transmission parameters of that frame. ThePLS1 enables the receiver to access and decode the PLS2 data, whichcontains the parameters to access the DP of interest. The PLS2 iscarried in every frame and split into two main parts: PLS2-STAT data andPLS2-DYN data. The static and dynamic portion of PLS2 data is followedby padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

Preamble signaling data carries 21 bits of information that are neededto enable the receiver to access PLS data and trace DPs within the framestructure. Details of the preamble signaling data are as follows:

PHY_PROFILE: This 3-bit field indicates the PHY profile type of thecurrent frame. The mapping of different PHY profile types is given inbelow table 5.

TABLE 5 Value PHY profile 000 Base profile 001 Handheld profile 010Advanced profiled 011~110 Reserved 111 FEF

FFT_SIZE: This 2 bit field indicates the FFT size of the current framewithin a frame-group, as described in below table 6.

TABLE 6 Value FFT size 00  8K FFT 01 16K FFT 10 32K FFT 11 Reserved

GI_FRACTION: This 3 bit field indicates the guard interval fractionvalue in the current super-frame, as described in below table 7.

TABLE 7 Value GI_FRACTION 000 1/5  001 1/10 010 1/20 011 1/40 100 1/80101  1/160 110~111 Reserved

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in thecurrent frame. If this field is set to ‘1’, emergency alert service(EAS) is provided in the current frame. If this field set to ‘0’, EAS isnot carried in the current frame. This field can be switched dynamicallywithin a super-frame.

PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobilemode or fixed mode for the current frame in the current frame-group. Ifthis field is set to ‘0’, mobile pilot mode is used. If the field is setto ‘1’, the fixed pilot mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used forthe current frame in the current frame-group. If this field is set tovalue ‘1’, tone reservation is used for PAPR reduction. If this field isset to ‘0’, PAPR reduction is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile typeconfigurations of the frame repetition units (FRU) that are present inthe current super-frame. All profile types conveyed in the currentsuper-frame are identified in this field in all preambles in the currentsuper-frame. The 3-bit field has a different definition for eachprofile, as show in below table 8.

TABLE 8 Current Current Current Current PHY_PROFILE = PHY_PROFILE =PHY_PROFILE = PHY_PROFILE = ‘000’ ‘001’ ‘010’ ‘111’ (base) (handheld)(advanced) (FEF) FRU_CONFIGURE = Only base Only handheld Only advancedOnly FEF 000 profile present profile present profile present presentFRU_CONFIGURE = Handheld Base Base Base 1XX profile present profilepresent profile present profile present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile present profile present profilepresent profile present FRU_CONFIGURE = FEF present FEF present FEFpresent Advanced XX1 profile present

RESERVED: This 7-bit field is reserved for future use.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. As abovementioned, the PLS1 data remain unchanged for the entire duration of oneframe-group. The detailed definition of the signaling fields of the PLS1data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signalingdata excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames perFRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload datacarried in the frame-group. PAYLOAD_TYPE is signaled as shown in table9.

TABLE 9 Value Payload type 1XX TS stream is transmitted X1X IP stream istransmitted XX1 GS stream is transmitted

NUM_FSS: This 2-bit field indicates the number of FSS symbols in thecurrent frame.

SYSTEM_VERSION: This 8-bit field indicates the version of thetransmitted signal format. The SYSTEM_VERSION is divided into two 4-bitfields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate majorversion information. A change in the major version field indicates anon-backward-compatible change. The default value is ‘0000’. For theversion described in this standard, the value is set to ‘0000’.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minorversion information. A change in the minor version field isbackward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographiccell in an ATSC network. An ATSC cell coverage area may consist of oneor more frequencies, depending on the number of frequencies used perFuturecast UTB system. If the value of the CELL_ID is not known orunspecified, this field is set to ‘0’.

NETWORK_ID: This is a 16-bit field which uniquely identifies the currentATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTBsystem within the ATSC network. The Futurecast UTB system is theterrestrial broadcast system whose input is one or more input streams(TS, IP, GS) and whose output is an RF signal. The Futurecast UTB systemcarries one or more PHY profiles and FEF, if any. The same FuturecastUTB system may carry different input streams and use different RFfrequencies in different geographical areas, allowing local serviceinsertion. The frame structure and scheduling is controlled in one placeand is identical for all transmissions within a Futurecast UTB system.One or more Futurecast UTB systems may have the same SYSTEM_ID meaningthat they all have the same physical layer structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH,FRU_GI_FRACTION, and RESERVED which are used to indicate the FRUconfiguration and the length of each frame type. The loop size is fixedso that four PHY profiles (including a FEF) are signaled within the FRU.If NUM_FRAME_FRU is less than 4, the unused fields are filled withzeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the(i+1)th (i is the loop index) frame of the associated FRU. This fielduses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)thframe of the associated FRU. Using FRU_FRAME_LENGTH together withFRU_GI_FRACTION, the exact value of the frame duration can be obtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fractionvalue of the (i+1)th frame of the associated FRU. FRU_GI_FRACTION issignaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2protection. The FEC type is signaled according to table 10. The detailsof the LDPC codes will be described later.

TABLE 10 Contents PLS2 FEC type 00 4K-1/4 and 7K-3/10 LDPC codes 01~11Reserved

PLS2_MOD: This 3-bit field indicates the modulation type used by thePLS2. The modulation type is signaled according to table 11.

TABLE 11 Value PLS2_MODE 000 BPSK 001 QPSK 010 QAM-16 011 NUQ-64 100~111Reserved

PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, thesize (specified as the number of QAM cells) of the collection of fullcoded blocks for PLS2 that is carried in the current frame-group. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, ofthe PLS2-STAT for the current frame-group. This value is constant duringthe entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of thePLS2-DYN for the current frame-group. This value is constant during theentire duration of the current frame-group.

PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetitionmode is used in the current frame-group. When this field is set to value‘1’, the PLS2 repetition mode is activated. When this field is set tovalue ‘0’, the PLS2 repetition mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block,the size (specified as the number of QAM cells) of the collection ofpartial coded blocks for PLS2 carried in every frame of the currentframe-group, when PLS2 repetition is used. If repetition is not used,the value of this field is equal to 0. This value is constant during theentire duration of the current frame-group.

PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used forPLS2 that is carried in every frame of the next frame-group. The FECtype is signaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used forPLS2 that is carried in every frame of the next frame-group. Themodulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2repetition mode is used in the next frame-group. When this field is setto value ‘1’, the PLS2 repetition mode is activated. When this field isset to value ‘0’, the PLS2 repetition mode is deactivated.

PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal_full_block,The size (specified as the number of QAM cells) of the collection offull coded blocks for PLS2 that is carried in every frame of the nextframe-group, when PLS2 repetition is used. If repetition is not used inthe next frame-group, the value of this field is equal to 0. This valueis constant during the entire duration of the current frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-STAT for the next frame-group. This value is constantin the current frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-DYN for the next frame-group. This value is constantin the current frame-group.

PLS2_AP_MODE: This 2-bit field indicates whether additional parity isprovided for PLS2 in the current frame-group. This value is constantduring the entire duration of the current frame-group. The below table12 gives the values of this field. When this field is set to ‘00’,additional parity is not used for the PLS2 in the current frame-group.

TABLE 12 Value PLS2-AP mode 00 AP is not provided 01 AP1 mode 10~11Reserved

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified asthe number of QAM cells) of the additional parity bits of the PLS2. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parityis provided for PLS2 signaling in every frame of next frame-group. Thisvalue is constant during the entire duration of the current frame-group.The table 12 defines the values of this field

PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specifiedas the number of QAM cells) of the additional parity bits of the PLS2 inevery frame of the next frame-group. This value is constant during theentire duration of the current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT dataare the same within a frame-group, while the PLS2-DYN data provideinformation that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in thecurrent frame-group. If this field is set to ‘1’, the FIC is provided inthe current frame. If this field set to ‘0’, the FIC is not carried inthe current frame. This value is constant during the entire duration ofthe current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) isused in the current frame-group. If this field is set to ‘1’, theauxiliary stream is provided in the current frame. If this field set to‘0’, the auxiliary stream is not carried in the current frame. Thisvalue is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within thecurrent frame. The value of this field ranges from 1 to 64, and thenumber of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaledaccording to the below table 13.

TABLE 13 Value DP Type 000 DP Type 1 001 DP Type 2 010~111 reserved

DP_GROUP_ID: This 8-bit field identifies the DP group with which thecurrent DP is associated. This can be used by a receiver to access theDPs of the service components associated with a particular service,which will have the same DP_GROUP_ID.

BASE_DP_ID: This 6-bit field indicates the DP carrying service signalingdata (such as PSI/SI) used in the Management layer. The DP indicated byBASE_DP_ID may be either a normal DP carrying the service signaling dataalong with the service data or a dedicated DP carrying only the servicesignaling data

DP_FEC_TYPE: This 2-bit field indicates the FEC type used by theassociated DP. The FEC type is signaled according to the below table 14.

TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC 10~11 Reserved

DP_COD: This 4-bit field indicates the code rate used by the associatedDP. The code rate is signaled according to the below table 15.

TABLE 15 Value Code rate 0000 5/15 0001 6/15 0010 7/15 0011 8/15 01009/15 0101 10/15  0110 11/15  0111 12/15  1000 13/15  1001~1111 Reserved

DP_MOD: This 4-bit field indicates the modulation used by the associatedDP. The modulation is signaled according to the below table 16.

TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode is used inthe associated DP. If this field is set to value ‘1’, SSD is used. Ifthis field is set to value ‘0’, SSD is not used.

The following field appears only if PHY_PROFILE is equal to ‘010’, whichindicates the advanced profile:

DP_MIMO: This 3-bit field indicates which type of MIMO encoding processis applied to the associated DP. The type of MIMO encoding process issignaled according to the table 17.

TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM 010~111 reserved

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. Avalue of ‘0’ indicates that one TI group corresponds to one frame andcontains one or more TI-blocks. A value of ‘1’ indicates that one TIgroup is carried in more than one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE fieldas follows:

If the DP_TI_TYPE is set to the value ‘1’, this field indicates PI, thenumber of the frames to which each TI group is mapped, and there is oneTI-block per TI group (NTI=1). The allowed PI values with 2-bit fieldare defined in the below table 18.

If the DP_TI_TYPE is set to the value ‘0’, this field indicates thenumber of TI-blocks NTI per TI group, and there is one TI group perframe (Pi=1). The allowed PI values with 2-bit field are defined in thebelow table 18.

TABLE 18 2-bit field PI NTI 00 1 1 01 2 2 10 4 3 11 8 4

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (IJUMP)within the frame-group for the associated DP and the allowed values are1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’, ‘10’, or ‘11’,respectively). For DPs that do not appear every frame of theframe-group, the value of this field is equal to the interval betweensuccessive frames. For example, if a DP appears on the frames 1, 5, 9,13, etc., this field is set to ‘4’. For DPs that appear in every frame,this field is set to ‘1’.

DP_TI_BYPASS: This 1-bit field determines the availability of timeinterleaver 5050. If time interleaving is not used for a DP, it is setto ‘1’. Whereas if time interleaving is used it is set to ‘0’.

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the firstframe of the super-frame in which the current DP occurs. The value ofDP_FIRST_FRAME_IDX ranges from 0 to 31

DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value ofDP_NUM_BLOCKS for this DP. The value of this field has the same range asDP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload datacarried by the given DP. DP_PAYLOAD_TYPE is signaled according to thebelow table 19.

TABLE 19 Value Payload Type 00 TS. 01 IP 10 GS 11 reserved

DP_INBAND_MODE: This 2-bit field indicates whether the current DPcarries in-band signaling information. The in-band signaling type issignaled according to the below table 20.

TABLE 20 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of thepayload carried by the given DP. It is signaled according to the belowtable 21 when input payload types are selected.

TABLE 21 If If If DP_PAY- DP_PAY- DP_PAY- LOAD_TYPE LOAD_TYPE LOAD_TYPEValue Is TS Is IP Is GS 00 MPEG2-TS IPv4 (Note) 01 Reserved IPv6Reserved 10 Reserved Reserved Reserved 11 Reserved Reserved Reserved

DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used inthe Input Formatting block. The CRC mode is signaled according to thebelow table 22.

TABLE 22 Value CRC mode 00 Not used 01 CRC-8 10 CRC-16 11 CRC-32

DNP_MODE: This 2-bit field indicates the null-packet deletion mode usedby the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP MODEis signaled according to the below table 23. If DP_PAYLOAD_TYPE is notTS (‘00’), DNP_MODE is set to the value ‘00’.

TABLE 23 Value Null-packet deletion mode 00 Not used 01 DNP-NORMAL 10DNP-OFFSET 11 reserved

ISSY_MODE: This 2-bit field indicates the ISSY mode used by theassociated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The ISSY_MODE issignaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS(‘00’), ISSY_MODE is set to the value ‘00’.

TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10 ISSY-BBF 11 reserved

HC_MODE_TS: This 2-bit field indicates the TS header compression modeused by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). TheHC_MODE_TS is signaled according to the below table 25.

TABLE 25 Value Header compression mode 00 HC_MODE_TS 1 01 HC_MODE_TS 210 HC_MODE_TS 3 11 HC_MODE_TS 4

HC_MODE_IP: This 2-bit field indicates the IP header compression modewhen DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaledaccording to the below table 26.

TABLE 26 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

PID: This 13-bit field indicates the PID number for TS headercompression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS isset to ‘01’ or ‘10’.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to ‘1’:

FIC_VERSION: This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, ofthe FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX_FLAG is equal to ‘1’:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams.Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicatingthe type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use forsignaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The values of thePLS2-DYN data may change during the duration of one frame-group, whilethe size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the currentframe within the super-frame. The index of the first frame of thesuper-frame is set to ‘0’.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration will change. The nextsuper-frame with changes in the configuration is indicated by the valuesignaled within this field. If this field is set to the value ‘0000’, itmeans that no scheduled change is foreseen: e.g., value ‘1’ indicatesthat there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration (i.e., the contents of theFIC) will change. The next super-frame with changes in the configurationis indicated by the value signaled within this field. If this field isset to the value ‘0000’, it means that no scheduled change is foreseen:e.g. value ‘0001’ indicates that there is a change in the nextsuper-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe theparameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position ofthe first of the DPs using the DPU addressing scheme. The DP_START fieldhas differing length according to the PHY profile and FFT size as shownin the below table 27.

TABLE 27 DP_START field size PHY profile 64K 16K Base 13 bits 15 bitsHandheld — 13 bits Advanced 13 bits 15 bits

DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks inthe current TI group for the current DP. The value of DP_NUM_BLOCKranges from 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with theEAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in thecurrent frame. This bit is the same value as the EAC_FLAG in thepreamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version numberof a wake-up indication.

If the EAC_FLAG field is equal to ‘1’, the following 12 bits areallocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to‘0’, the following 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of theEAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames beforethe frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to ‘1’:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use forsignaling auxiliary streams. The meaning of this field depends on thevalue of AUX_STREAM_TYPE in the configurable PLS2-STAT.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS2.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummycells are mapped into the active carriers of the OFDM symbols in theframe. The PLS1 and PLS2 are first mapped into one or more FSS(s). Afterthat, EAC cells, if any, are mapped immediately following the PLS field,followed next by FIC cells, if any. The DPs are mapped next after thePLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next.The details of a type of the DP will be described later. In some case,DPs may carry some special data for EAS or service signaling data. Theauxiliary stream or streams, if any, follow the DPs, which in turn arefollowed by dummy cells. Mapping them all together in the abovementioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummydata cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

PLS cells are mapped to the active carriers of FSS(s). Depending on thenumber of cells occupied by PLS, one or more symbols are designated asFSS(s), and the number of FSS(s) N_FSS is signaled by NUM_FSS in PLS1.The FSS is a special symbol for carrying PLS cells. Since robustness andlatency are critical issues in the PLS, the FSS(s) has higher density ofpilots allowing fast synchronization and frequency-only interpolationwithin the FSS.

PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-downmanner as shown in an example in FIG. 17. The PLS1 cells are mappedfirst from the first cell of the first FSS in an increasing order of thecell index. The PLS2 cells follow immediately after the last cell of thePLS1 and mapping continues downward until the last cell index of thefirst FSS. If the total number of required PLS cells exceeds the numberof active carriers of one FSS, mapping proceeds to the next FSS andcontinues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC orboth are present in the current frame, they are placed between PLS and“normal” DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

EAC is a dedicated channel for carrying EAS messages and links to theDPs for EAS. EAS support is provided but EAC itself may or may not bepresent in every frame. EAC, if any, is mapped immediately after thePLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliarystreams or dummy cells other than the PLS cells. The procedure ofmapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasingorder of the cell index as shown in the example in FIG. 18. Depending onthe EAS message size, EAC cells may occupy a few symbols, as shown inFIG. 18.

EAC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required EAC cells exceeds the number of remainingactive carriers of the last FSS mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol, which has more activecarriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists.If FIC is not transmitted (as signaled in the PLS2 field), DPs followimmediately after the last cell of the EAC.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

(a) shows an example mapping of FIC cell without EAC and (b) shows anexample mapping of FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information toenable fast service acquisition and channel scanning. This informationprimarily includes channel binding information between DPs and theservices of each broadcaster. For fast scan, a receiver can decode FICand obtain information such as broadcaster ID, number of services, andBASE_DP_ID. For fast service acquisition, in addition to FIC, base DPcan be decoded using BASE_DP_ID. Other than the content it carries, abase DP is encoded and mapped to a frame in exactly the same way as anormal DP. Therefore, no additional description is required for a baseDP. The FIC data is generated and consumed in the Management Layer. Thecontent of FIC data is as described in the Management Layerspecification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAGparameter in the static part of the PLS2. If FIC is used, FIC_FLAG isset to ‘1’ and the signaling field for FIC is defined in the static partof PLS2. Signaled in this field are FIC_VERSION, and FIC_LENGTH_BYTE.FIC uses the same modulation, coding and time interleaving parameters asPLS2. FIC shares the same signaling parameters such as PLS2_MOD andPLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or EAC ifany. FIC is not preceded by any normal DPs, auxiliary streams or dummycells. The method of mapping FIC cells is exactly the same as that ofEAC which is again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of thePLS2 in an increasing order of the cell index as shown in an example in(a). Depending on the FIC data size, FIC cells may be mapped over a fewsymbols, as shown in (b).

FIC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required FIC cells exceeds the number of remainingactive carriers of the last FSS, mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol which has more activecarriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC,and FIC cells are mapped from the next cell of the EAC in an increasingorder of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed byauxiliary streams, if any, and dummy cells.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

shows type 1 DP and (b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cellsof the DPs are mapped. A DP is categorized into one of two typesaccording to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2.FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs.Type 1 DPs are first mapped in the increasing order of cell index, andthen after reaching the last cell index, the symbol index is increasedby one. Within the next symbol, the DP continues to be mapped in theincreasing order of cell index starting from p=0. With a number of DPsmapped together in one frame, each of the Type 1 DPs are grouped intime, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, andthen after reaching the last OFDM symbol of the frame, the cell indexincreases by one and the symbol index rolls back to the first availablesymbol and then increases from that symbol index. After mapping a numberof DPs together in one frame, each of the Type 2 DPs are grouped infrequency together, similar to FDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with onerestriction; Type 1 DPs always precede Type 2 DPs. The total number ofOFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total numberof OFDM cells available for transmission of DPs:

D _(DP1) +D _(DP2) ≦D _(DP)  [Equation 2]

where DDP1 is the number of OFDM cells occupied by Type 1 DPs, DDP2 isthe number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are allmapped in the same way as Type 1 DP, they all follow “Type 1 mappingrule”. Hence, overall, Type 1 mapping always precedes Type 2 mapping.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

shows an addressing of OFDM cells for mapping type 1 DPs and (b) showsan addressing of OFDM cells for mapping for type 2 DPs.

Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , DDP1-1) isdefined for the active data cells of Type 1 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 1DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately followingthe last cell carrying PLS in the last FSS. If EAC is transmitted andFIC is not in the corresponding frame, address 0 refers to the cellimmediately following the last cell carrying EAC. If FIC is transmittedin the corresponding frame, address 0 refers to the cell immediatelyfollowing the last cell carrying FIC. Address 0 for Type 1 DPs can becalculated considering two different cases as shown in (a). In theexample in (a), PLS, EAC and FIC are assumed to be all transmitted.Extension to the cases where either or both of EAC and FIC are omittedis straightforward. If there are remaining cells in the FSS aftermapping all the cells up to FIC as shown on the left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , DDP2-1) isdefined for the active data cells of Type 2 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 2DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For thefirst case shown on the left side of (b), cells in the last FSS areavailable for Type 2 DP mapping. For the second case shown in themiddle, FIC occupies cells of a normal symbol, but the number of FICcells on that symbol is not larger than CFSS. The third case, shown onthe right side in (b), is the same as the second case except that thenumber of FIC cells mapped on that symbol exceeds CFSS.

The extension to the case where Type 1 DP(s) precede Type 2 DP(s) isstraightforward since PLS, EAC and FIC follow the same “Type 1 mappingrule” as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DPin a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A CellMapper 7010 may map the cells produced by the TIs for each of the DPs. ATime interleaver 5050 outputs a series of TI-blocks and each TI-blockcomprises a variable number of XFECBLOCKs which is in turn composed of aset of cells. The number of cells in an XFECBLOCK, Ncells, is dependenton the FECBLOCK size, Nldpc, and the number of transmitted bits perconstellation symbol. A DPU is defined as the greatest common divisor ofall possible values of the number of cells in a XFECBLOCK, Ncells,supported in a given PHY profile. The length of a DPU in cells isdefined as LDPU. Since each PHY profile supports different combinationsof FECBLOCK size and a different number of bits per constellationsymbol, LDPU is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention before bit interleaving. As above mentioned, Data FECencoder may perform the FEC encoding on the input BBF to generateFECBLOCK procedure using outer coding (BCH), and inner coding (LDPC).The illustrated FEC structure corresponds to the FECBLOCK. Also, theFECBLOCK and the FEC structure have same value corresponding to a lengthof LDPC codeword.

The BCH encoding is applied to each BBF (Kbch bits), and then LDPCencoding is applied to BCH-encoded BBF (Kldpc bits=Nbch bits) asillustrated in FIG. 22.

The value of Nldpc is either 64800 bits (long FECBLOCK) or 16200 bits(short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a longFECBLOCK and a short FECBLOCK, respectively.

TABLE 28 BCH error LDPC correction Nbch- Rate Nldpc Kldpc Kbchcapability Kbch 5/15 64800 21600 21408 12 192 6/15 25920 25728 7/1530240 30048 8/15 34560 34368 9/15 38880 38688 10/15  43200 43008 11/15 47520 47328 12/15  51840 51648 13/15  56160 55968

TABLE 29 BCH error LDPC correction Nbch − Rate Nldpc Kldpc Kbchcapability Kbch 5/15 16200 5400 5232 12 168 6/15 6480 6312 7/15 75607392 8/15 8640 8472 9/15 9720 9552 10/15  10800 10632 11/15  11880 1171212/15  12960 12792 13/15  14040 13872

The details of operations of the BCH encoding and LDPC encoding are asfollows:

A 12-error correcting BCH code is used for outer encoding of the BBF.The BCH generator polynomial for short FECBLOCK and long FECBLOCK areobtained by multiplying together all polynomials.

LDPC code is used to encode the output of the outer BCH encoding. Togenerate a completed Bldpc (FECBLOCK), Pldpc (parity bits) is encodedsystematically from each Ildpc (BCH-encoded BBF), and appended to Ildpc.The completed Bldpc (FECBLOCK) are expressed as follow Equation.

B _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ⁻¹,p ₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹]  [Equation 3]

The parameters for long FECBLOCK and short FECBLOCK are given in theabove table 28 and 29, respectively.

The detailed procedure to calculate Nldpc-Kldpc parity bits for longFECBLOCK, is as follows:

1) Initialize the parity bits,

p ₀ =p ₁ =p ₂ = . . . =p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹=0  [Equation 4]

2) Accumulate the first information bit—i0, at parity bit addressesspecified in the first row of an addresses of parity check matrix. Thedetails of addresses of parity check matrix will be described later. Forexample, for rate 13/15:

p ₉₈₃ =p ₉₈₃ ⊕i ₀ p ₂₈₁₅ =p ₂₈₁₅ ⊕i ₀

p ₄₈₃₇ =p ₄₈₃₇ ⊕i ₀ p ₄₉₈₉ =p ₄₉₈₉ ⊕i ₀

p ₆₁₃₈ =p ₆₁₃₈ ⊕i ₀ p ₆₄₅₈ =p ₆₄₅₈ ⊕i ₀

p ₆₉₂₁ =p ₆₉₂₁ ⊕i ₀ p ₆₉₇₄ =p ₆₉₇₄ ⊕i ₀

p ₇₅₇₂ =p ₇₅₇₂ ⊕i ₀ p ₈₂₆₀ =p ₈₂₆₀ ⊕i ₀

p ₈₄₉₆ =p ₈₄₉₆ ⊕i ₀  [Equation 5]

3) For the next 359 information bits, is, s=1, 2, . . . , 359 accumulateis at parity bit addresses using following Equation.

{(x+(s mod 360)×Q _(ldpc)} mod(N _(ldpc) −K _(ldpc))  [Equation 6]

where x denotes the address of the parity bit accumulator correspondingto the first bit i0, and Qldpc is a code rate dependent constantspecified in the addresses of parity check matrix. Continuing with theexample, Qldpc=24 for rate 13/15, so for information bit i1, thefollowing operations are performed:

p ₁₀₀₇ =p ₁₀₀₇ ⊕i ₁ p ₂₈₃₉ =p ₂₈₃₉ ⊕i ₁

p ₄₈₆₁ =p ₄₈₆₁ ⊕i ₁ p ₅₀₁₃ =p ₅₀₁₃ ⊕i ₁

p ₆₁₆₂ =p ₆₁₆₂ ⊕i ₁ p ₆₄₈₂ =p ₆₄₈₂ ⊕i ₁

p ₆₉₄₅ =p ₆₉₄₅ ⊕i ₁ p ₆₉₉₈ =p ₆₉₉₈ ⊕i ₁

p ₇₅₉₆ =p ₇₅₉₆ ⊕i ₁ p ₈₂₈₄ =p ₈₄₈₄ ⊕i ₁

p ₈₅₂₀ =p ₈₅₂₀ ⊕i ₁  [Equation 7]

4) For the 361st information bit i360, the addresses of the parity bitaccumulators are given in the second row of the addresses of paritycheck matrix. In a similar manner the addresses of the parity bitaccumulators for the following 359 information bits is, s=361, 362, . .. , 719 are obtained using the Equation 6, where x denotes the addressof the parity bit accumulator corresponding to the information bit i360,i.e., the entries in the second row of the addresses of parity checkmatrix.

5) In a similar manner, for every group of 360 new information bits, anew row from addresses of parity check matrixes used to find theaddresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bitsare obtained as follows:

6) Sequentially perform the following operations starting with i=1

p _(i) =p _(i) ⊕p _(i−1) , i=1,2, . . . ,N _(ldpc) −K_(ldpc)−1  [Equation 8]

where final content of pi, i=0, 1, . . . N_(ldpc)−K_(ldpc)−1 is equal tothe parity bit pi.

TABLE 30 Code Rate Qldpc 5/15 120 6/15 108 7/15 96 8/15 84 9/15 7210/15  60 11/15  48 12/15  36 13/15  24

This LDPC encoding procedure for a short FECBLOCK is in accordance witht LDPC encoding procedure for the long FECBLOCK, except replacing thetable 30 with table 31, and replacing the addresses of parity checkmatrix for the long FECBLOCK with the addresses of parity check matrixfor the short FECBLOCK.

TABLE 31 Code Rate Qldpc 5/15 30 6/15 27 7/15 24 8/15 21 9/15 18 10/15 15 11/15  12 12/15  9 13/15  6

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

The outputs of the LDPC encoder are bit-interleaved, which consists ofparity interleaving followed by Quasi-Cyclic Block (QCB) interleavingand inner-group interleaving.

shows Quasi-Cyclic Block (QCB) interleaving and (b) shows inner-groupinterleaving.

The FECBLOCK may be parity interleaved. At the output of the parityinterleaving, the LDPC codeword consists of 180 adjacent QC blocks in along FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QCblock in either a long or short FECBLOCK consists of 360 bits. Theparity interleaved LDPC codeword is interleaved by QCB interleaving. Theunit of QCB interleaving is a QC block. The QC blocks at the output ofparity interleaving are permutated by QCB interleaving as illustrated inFIG. 23, where Ncells=64800/η mod or 16200/η mod according to theFECBLOCK length. The QCB interleaving pattern is unique to eachcombination of modulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed accordingto modulation type and order (mod) which is defined in the below table32. The number of QC blocks for one inner-group, NQCB_IG, is alsodefined.

TABLE 32 Modulation type ηmod NQCB_IG QAM-16 4 2 NUC-16 4 4 NUQ-64 6 3NUC-64 6 6 NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-1024 10 10

The inner-group interleaving process is performed with NQCB_IG QC blocksof the QCB interleaving output. Inner-group interleaving has a processof writing and reading the bits of the inner-group using 360 columns andNQCB_IG rows. In the write operation, the bits from the QCB interleavingoutput are written row-wise. The read operation is performed column-wiseto read out m bits from each row, where m is equal to 1 for NUC and 2for NUQ.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b) shows acell-word demultiplexing for 10 bpcu MIMO.

Each cell word (c0,l, c1,l, . . . , cη mod−1,l) of the bit interleavingoutput is demultiplexed into (d1,0,m, d1,1,m . . . , d1,η mod−1,m) and(d2,0,m, d2,1,m . . . , d2,η mod−1,m) as shown in (a), which describesthe cell-word demultiplexing process for one XFECBLOCK.

For the 10 bpcu MIMO case using different types of NUQ for MIMOencoding, the Bit Interleaver for NUQ-1024 is re-used. Each cell word(c0,l, c1,l, . . . , c9,l) of the Bit Interleaver output isdemultiplexed into (d1,0,m, d1,1,m . . . , d1,3,m) and (d2,0,m, d2,1,m .. . , d2,5,m), as shown in (b).

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

(a) to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of timeinterleaving (TI) may be set differently for each DP.

The following parameters, which appear in part of the PLS2-STAT data,configure the TI:

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’indicates the mode with multiple TI blocks (more than one TI block) perTI group. In this case, one TI group is directly mapped to one frame (nointer-frame interleaving). ‘1’ indicates the mode with only one TI blockper TI group. In this case, the TI block may be spread over more thanone frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TIblocks NTI per TI group. For DP_TI_TYPE ‘1’, this parameter is thenumber of frames PI spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximumnumber of XFECBLOCKs per TI group.

DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number ofthe frames IJUMP between two successive frames carrying the same DP of agiven PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not usedfor a DP, this parameter is set to ‘1’. It is set to ‘0’ if timeinterleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is usedto represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group,time interleaving operation, and TI mode are not considered. However,the Delay Compensation block for the dynamic configuration informationfrom the scheduler will still be required. In each DP, the XFECBLOCKsreceived from the SSD/MIMO encoding are grouped into TI groups. That is,each TI group is a set of an integer number of XFECBLOCKs and willcontain a dynamically variable number of XFECBLOCKs. The number ofXFECBLOCKs in the TI group of index n is denoted by NxBLOCK_Group(n) andis signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note thatNxBLOCK_Group(n) may vary from the minimum value of 0 to the maximumvalue NxBLOCK_Group_MAX (corresponding to DP_NUM_BLOCK_MAX) of which thelargest value is 1023.

Each TI group is either mapped directly onto one frame or spread over PIframes. Each TI group is also divided into more than one TI blocks(NTI), where each TI block corresponds to one usage of time interleavermemory. The TI blocks within the TI group may contain slightly differentnumbers of XFECBLOCKs. If the TI group is divided into multiple TIblocks, it is directly mapped to only one frame. There are three optionsfor time interleaving (except the extra option of skipping the timeinterleaving) as shown in the below table 33.

TABLE 33 Mode Description Option-1 Each TI group contains one TI blockand is mapped directly to one frame as shown in (a). This option issignaled in the PLS2-STAT by DP_TI_TYPE = ‘0’ and DP_TI_LENGTH = ‘1’(N_(TI) = 1). Option-2 Each TI group contains one TI block and is mappedto more than one frame. (b) shows an example, where one TI group ismapped to two frames, i.e., DP_TI_LENGTH = ‘2’ (P_(I) = 2) andDP_FRAME_INTERVAL (I_(JUMP) = 2). This provides greater time diversityfor low data-rate services. This option is signaled in the PLS2-STAT byDP_TI_TYPE = ‘1’. Option-3 Each TI group is divided into multiple TIblocks and is mapped directly to one frame as shown in (c). Each TIblock may use full TI memory, so as to provide the maximum bit-rate fora DP. This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE =‘0’ and DP_TI_LENGTH = NTI, while P_(I) = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKsfrom the SSD/MIMO encoding block). Assume that input XFECBLOCKs aredefined as

(d_(n, s, 0, 0), d_(n, s, 0, 1), …  , d_(n, s, 0, N_(cells) − 1), d_(n, s, 1, 0), …  , d_(n, s, 1, N_(cells) − 1), …  , d_(n, s, N_(xBLOCK_TI)(n, s) − 1, 0), …  , d_(n, s, N_(xBLOCK_TI)(n, s) − 1, N_(cells) − 1)),

where d_(n,s,r,q) is the qth cell of the rth XFECBLOCK in the sth TIblock of the nth TI group and represents the outputs of SSD and MIMOencodings as follows

$d_{n,s,r,q} = \{ {\begin{matrix}{f_{n,s,r,q},} & {{the}\mspace{14mu} {output}\mspace{14mu} {of}\mspace{14mu} {SSD}\mspace{14mu} \ldots \mspace{14mu} {encoding}} \\{g_{n,s,r,q},} & {{the}\mspace{14mu} {output}\mspace{14mu} {of}\mspace{14mu} {MIMO}\mspace{14mu} {encoding}}\end{matrix}.} $

In addition, assume that output XFECBLOCKs from the time interleaver5050 are defined as

(h_(n, s, 0), h_(n, s, 1), …  , h_(n, s, i), …  , h_(n, s, N_(xBLOCK_TI)(n, s) × N_(cells) − 1)),

where h_(n,s,i) is the ith output cell (for i=0, . . . N_(xBLOCK) _(_)_(TI)(n,s)×N_(cells)−1) in the sth TI block of the nth TI group.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to the firstbank. The second TI-block is written to the second bank while the firstbank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI blockof the nth TI group, the number of rows N_(r) of a TI memory is equal tothe number of cells N_(cells), i.e., N_(r)=N_(cells) while the number ofcolumns N_(c) is equal to the number N_(xBLOCK) _(_) _(TI)(n,s).

FIG. 26 illustrates a basic operation of a twisted row-column blockinterleaver according to an exemplary embodiment of the presentinvention.

FIG. 26A illustrates a writing operation in a time interleaver and FIG.26B illustrates a reading operation in the time interleaver. Asillustrated in FIG. 26A, a first XFECBLOCK is written in a first columnof a time interleaving memory in a column direction and a secondXFECBLOCK is written in a next column, and such an operation iscontinued. In addition, in an interleaving array, a cell is read in adiagonal direction. As illustrated in FIG. 26B, while the diagonalreading is in progress from a first row (to a right side along the rowstarting from a leftmost column) to a last row, N_(r) cells are read. Indetail, when it is assumed that z_(n,s,i) (i=0, . . . N_(r)N_(c)) is atime interleaving memory cell position to be sequentially read, thereading operation in the interleaving array is executed by calculating arow index R_(n,s,i) a column index C_(n,s,i) and associated twistparameter T_(n,s,i) as shown in an equation given below.

$\begin{matrix}{{{GENERATE}( {R_{n,s,i},C_{n,s,i}} )} = \begin{Bmatrix}{{R_{n,s,i} = {{mod}( {i,N_{r}} )}},} \\{{T_{n,s,i} = {{mod}( {{S_{shift} \times R_{n,s,i}},N_{c}} )}},} \\{C_{n,s,i} = {{mod}( {{T_{n,s,i} + \lfloor \frac{i}{N_{r}} \rfloor},N_{c}} )}}\end{Bmatrix}} & \lbrack {{Equation}\mspace{14mu} 9} \rbrack\end{matrix}$

Where, S_(shift) is a common shift value for a diagonal reading processregardless of N_(xBLOCK TI) (n,s) and the shift value is decided byN_(xBLOCK TI MAX) given in PLS2-STAT as shown in an equation givenbelow.

$\begin{matrix}{{for}\{ {\begin{matrix}{\begin{matrix}{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} =} \\{N_{{xBLOCK\_ TI}{\_ MAX}} + 1}\end{matrix},} & {{{if}\mspace{14mu} N_{{xBLOCK\_ TI}{\_ MAX}}{mod}\; 2} = 0} \\{\begin{matrix}{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} =} \\N_{{xBLOCK\_ TI}{\_ MAX}}\end{matrix},} & {{{if}\mspace{14mu} N_{{xBLOCK\_ TI}{\_ MAX}}{mod}\; 2} = 1}\end{matrix},\mspace{79mu} {S_{shift} = \frac{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} - 1}{2}}} } & \lbrack {{Equation}\mspace{14mu} 10} \rbrack\end{matrix}$

Consequently, the cell position to be read is calculated by a coordinatex_(n,s,i)=N_(r) C_(n,s,i)+R_(n,s,i).

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another exemplary embodiment of the presentinvention.

In more detail, FIG. 27 illustrates an interleaving array in the timeinterleaving memory for respective time interleaving groups including avirtual XFECBLOCK when N_(xBLOCK) _(_) _(TI)(0,0)=3,N_(xBLOCK TI)(1,0)=6, and N_(xBLOCK TI)(2,0)=5.

A variable N_(xBLOCK TI)(n,s)=N, will be equal to or smaller thanN′_(xBLOCK) _(_) _(TI) _(_) _(MAX). Accordingly, in order for a receiverto achieve single memory interleaving regardless of N_(xBLOCK) _(_)_(TI) (n,s), the size of the interleaving array for the twistedrow-column block interleaver is set to a size ofN_(r)×N_(c)=N_(cells)×N′_(xBLOCK) _(_) _(TI) _(_) _(MAX) by insertingthe virtual XFECBLOCK into the time interleaving memory and a readingprocess is achieved as shown in an equation given below.

$\begin{matrix}{{{p = 0};}{for}{{i = 0};}{{i < {N_{cells}N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime}}};}{i = {i + 1}}\begin{Bmatrix}{{{GENERATE}( {R_{n,s,i},C_{n,s,i}} )};} \\{V_{i} = {{N_{r}C_{n,s,j}} + R_{n,s,j}}} \\{{{if}\mspace{14mu} V_{i}} < {N_{cells}{N_{xBLOCK\_ TI}( {n,s} )}}} \\\{ {{Z_{n,s,p} = V_{i}};{p = {p + 1}};} \}\end{Bmatrix}} & \lbrack {{Equation}\mspace{14mu} 11} \rbrack\end{matrix}$

The number of the time interleaving groups is set to 3. An option of thetime interleaver is signaled in the PLS2-STAT by DP_TI_TYPE=‘0’,DP_FRAME_INTERVAL=‘1’, and DP_TI_LENGTH=‘1’, that is, NTI=1, IJUMP=1,and PI=1. The number of respective XFECBLOCKs per time interleavinggroup, of which Ncells=30 is signaled in PLS2-DYN data byNxBLOCK_TI(0,0)=3, NxBLOCK_TI(1,0)=6, and NxBLOCK_TI(2,0)=5 of therespective XFECBLOCKs. The maximum number of XFECBLOCKs is signaled inthe PLS2-STAT data by NxBLOCK_Group_MAX and this is continued to└N_(xBLOCK) _(_) _(Group) _(_) _(MAX)/N_(TI)┘=N_(xBLOCK) _(_) _(TI) _(_)_(MAX)=6.

FIG. 28 illustrates a diagonal reading pattern of the twisted row-columnblock interleaver according to the exemplary embodiment of the presentinvention.

In more detail, FIG. 28 illustrates a diagonal reading pattern fromrespective interleaving arrays having parameters N′_(xBLOCK TI MAX)=7and Sshift=(7−1)/2=3. In this case, during a reading process expressedby a pseudo code given above, when V_(i)≧N_(cells)N_(xBLOCK) _(_) _(TI)(n,s), a value of Vi is omitted and a next calculation value of Vi isused.

FIG. 29 illustrates XFECBLOCK interleaved from each interleaving arrayaccording to an exemplary embodiment of the present invention.

FIG. 29 illustrates XFECBLOCK interleaved from each interleaving arrayhaving parameters N_(xBLOCK) _(_) _(TI) _(_) _(MAX)=7 and Sshift=3according to an exemplary embodiment of the present invention.

FIG. 30 illustrates a block diagram of a synchronization & demodulationmodule of a broadcast signal receiver in detail according to oneembodiment of the present invention.

FIG. 30 illustrates a sub-modules included in the synchronization &demodulation module 9000 of FIG. 9.

The synchronization/demodulation module comprises a tuner 30010 fortuning to a broadcast signal, an ADC module 30020 for converting areceived analog signal to a digital signal, a preamble detecting module30030 for detecting a preamble included in a received signal, a guardsequence detecting module 30040 for detecting a guard sequence includedin a received signal, a waveform transform module 30050 for performingFFT on a received signal, a reference signal detecting module 30060 fordetecting a pilot signal included in a received signal; a channelequalizer 30070 for performing channel equalization by using anextracted guard sequence, an inverse waveform transform module 30100, atime domain reference signal detecting module 30090 for detecting apilot signal in the time domain, and a time/frequency synchronizationmodule 30100 for performing time/frequency synchronization of a receivedsignal by using a preamble and a pilot signal. The inverse waveformtransform module 30080 performs transformation with respect to theinverse FFT, which may be omitted according to a particular embodimentor replaced with a different module that performs the same or a similarfunction thereof.

FIG. 30 illustrates a case where the receiver processes a signalreceived by multiple antennas through multiple paths; identical modulesare shown in parallel, descriptions of which are not provided.

In the present invention, the receiver can detect and utilize a pilotsignal by using the reference signal detecting module 30060 and the timedomain reference signal detecting module 30090. The reference signaldetecting module 30060 can detect a pilot signal in the frequencydomain, and the receiver can perform synchronization and channelestimation by using the characteristics of the detected pilot signal.The time domain reference signal detecting module 30090 can detect apilot signal in the time domain of a received signal, and the receivercan perform synchronization and channel estimation by using thecharacteristics of the detected pilot signal. This document refers to atleast one of the module 30060 detecting a pilot signal in the frequencydomain and the module 30090 detecting a pilot signal in the time domainas a pilot signal detecting module. Also, in this document, a referencesignal is referred to as a pilot signal.

The receiver can detect a CP pattern included in a received signal andperform synchronization through coarse Auto-Frequency Control (AFC),fine AFC, and Common Phase Error (CPE) correction by using the detectedCP pattern. The receiver can detect pilot signals included in a receivedsignal by using the pilot signal detecting module and performtime/frequency synchronization by comparing the detected pilot signalswith those pilot signals known to the receiver.

The present invention attempts to design a CP pattern that achievesvarious goals and effects. First, the CP pattern according to thepresent invention attempts to reduce signaling information and simplifyinteraction in time interleaving and carrier mapping by maintaining theNumber of Active data carrier (NoA) in each OFDM symbol with respect tothe predetermined Number of active Carrier (NoC) and a predetermined SPpattern.

Also, the present invention attempts to change the NoC and the CPpattern according to the SP pattern to achieve the condition above. Alsothe CP pattern according to the present invention attempts to selectSP-bearing CP and non-SP-bearing CP fairly so that roughly evendistribution over spectrum and random position distribution overspectrum can be achieved to combat a frequency selective channel. Andthe CP pattern is composed so that the overall overhead of the CP can bepreserved and the number of CP positions can be reduced according as theNoC is reduced. The SP-bearing CP and non-SP-bearing CP may be referredto as SP-bearing CP and non-SP-bearing CP. The SP-bearing CP representsthe CP of which the position overlaps with the position of the SP, whilethe non-SP-bearing CP represents the CP of which the position does notoverlap with the position of the SP.

The pattern or position information of a CP can be stored in the memoryof a transmitter or a receiver in the form of an index table. However,since the SP pattern used in a broadcast system has been diversified andthe mode of the NoC has been increased, the size of the index table hasincreased to occupy a large portion of the memory. Therefore, thepresent invention tries to solve the aforementioned problem and toprovide a CP pattern that satisfies the goal and effects of the CPpattern described above.

In this document, the interval in the frequency domain among SPsincluded in an SP pattern is denoted by Dx, and the interval in the timedomain is denoted by Dy. In other words, Dx represents separation amongcarriers bearing pilots along the frequency axis, while Dy representsthe number of symbols forming one scattered pilot sequence along thetime axis.

In the case of a broadcast system, spectrum masks may vary depending oncountries and regions. Therefore, depending on the situation, bandwidthof a broadcast signal may have to be changed, and to this purpose, thepresent invention provides a flexible Number of Carriers (NoC)structure.

FIGS. 31 to 33 illustrate embodiments of a flexible NoC structure of abroadcast signal according to the present invention.

Two different methods can be used to compose a signal through theflexible NoC structure.

1) The minimum bandwidth and the minimum NoC according to the minimumbandwidth are determined, and by using the minimum bandwidth and theminimum NoC, NoC is extended by predetermined units. In this method, thenon-SP-bearing CP designed according to the minimum NoC is not changedaccording as the NoC is extended, but since the extended bandwidth isnot fully utilized, performance may be degraded. To this purpose, atable may have to be added to determine non-SP-bearing CP which is addedas the NoC is increased.

2) The maximum bandwidth and the maximum NoC according to the maximumbandwidth are determined, and by using the maximum NoC, NoC is reducedby predetermined units. In this method, pilots which mask out thenon-SP-bearing CP can be used by specifying a window corresponding tothe maximum NoC. In this case, the number of CPs is designed to have amargin so that performance degradation due to NoC reduction can beprevented. In other words, the system is designed so that the minimumNoC reduced from the maximum NoC can have a particular number ofnon-SP-bearing CPs. Also, this method can be used to support such a caserequiring additional narrow bandwidth or a smaller NoC. This method canbe expressed by Eq. 12 below.

NoC=NoC_Max−k*Δ  [Equation 12]

In Eq. 12, NoC represents the number of carriers, namely, the number ofsymbols included in one signal frame, which is the number of OFDMsubcarriers. Δ represents the control unit value, and k represents thecoefficient multiplied to the control unit value to determine the numberof carriers to be reduced. As shown in FIGS. 31 to 33, Δ can be changedaccording to the FFT size: Δ_8K-FFT=96, Δ_16K-FFT=192, andΔ_32K-FFT=384, respectively. k can take on one value from 0 to 4. k canalso be expressed by reduction coefficient (C_(red_coeff)). The maximumNoC (NoC_Max) differs by the FFT size, and as shown in FIGS. 31 to 33,the maximum NoC can be 6529 for 8K FFT, 13057 for 16K FFT, and 26113 for23 k FFT.

Depending on embodiments, the number of non-SP-bearing CPs can bedetermined by the maximum NoC or the minimum NoC. As shown in FIG. 31,the system can be structured so that the number of non-SP-bearing CPswith respect to the maximum NoC is 45, and the number of non-SP-bearingCPs with respect to the minimum NoC where k=4 is 43. However, in thiscase, performance in transmission and reception may be degraded if thebandwidth of the broadcast system is taken into consideration.Therefore, as shown in FIG. 32, the system can be designed so that whilethe bandwidth window is masked out as NoC is reduced from the maximumNoC, the number of non-SP-bearing CPs with respect to the minimum NoCbecomes 45, and inversely, the number of non-SP-bearing CPs with respectto the maximum NoC becomes 48 to prevent performance degradation. FIG.33 illustrates an embodiment of a method as shown in FIG. 32, where, inthe case of 8K FFT, the number of non-SP-bearing CPs changes from 45 to48; in the embodiment, NoC and the estimated number of CPs varyaccording to FFT sizes and the values of k.

The present invention composes a system such that NoC can be reduced inmultiples of Δ according to the needs from the maximum NoC as shown inEq. 12. Also, the system is further composed so that the number ofnon-SP-bearing CPs corresponds to 48 for 8K, 96 for 16K, and 192 for 96according to the FFT size in the case of the maximum NoC; variation ofthe number of non-SP-bearing CPs according to the increase of k can befound from FIGS. 31 to 33.

In what follows, described will be a method for maintaining a constantNoA in case flexible NoC is used as described above.

In case flexible NoC is supported, NoC can be extended or reduced inunits of Max (Dx); in this case, too, a constant on the number ofSP-bearing CPs and positions thereof is generated in order to maintainconstant NoA. In case NoC is extended or reduced in units of Dx, such aconstraint can be changed according to the SP pattern, FFT size, and kvalue.

FIGS. 34 to 37 illustrate cases according to one embodiment of thepresent invention, where constraints are generated to maintain aconstant NoA when NoC is changed according to FFT size.

As described above, in case flexible NoC is supported, NoC is reduced by96, 182, and 384 units according to k values and FFT sizes. However, theSP pattern is repeated by block units corresponding to Dx*Dy. Therefore,if the value of Δ being reduced does not correspond to the multiple ofthe Dx*Dy block, the pilot pattern configured for a constant NoA isviolated. This is so because the NoC may not correspond to the multipleof Dx*Dy since the NoC is reduced by the maximum Dx unit. This fact canbe expressed by the following equation.

MOD(NoC−1,Dx*Dy)  [Equation 13]

In Eq. 13, if the result value for k ranging from 0 to 4 is 0, NoA ismaintained, but in other cases, the pilot pattern needs to be changedsince the NoA is not maintained. This case occurs when the SP pattern is(Dx, Dy)={(32, 2), (16, 4), (32, 4)} in the case of 8K FFT and the SPpattern is (Dx, Dy)=(32, 4) in the case of 16K FFT.

FIG. 34 illustrates a case where the pilot pattern needs to be changedto support the constant NoA in case 8K FFT is used and the SP pattern(Dx, Dy)=(32, 2). In FIG. 34, in case 8K FFT is used and the SP pattern(Dx, Dy)=(32, 2), the value of MOD(NoC−1, Dx*Dy) is 0 for k=0, 2, 4; and32 for k=1, 3. Therefore, in case k=1, 3, the pilot pattern needs to bechanged to have a constant NoA.

FIG. 35 illustrates a case where the pilot pattern needs to be changedto support the constant NoA in case 8K FFT is used and the SP pattern(Dx, Dy)=(16, 4). In FIG. 35, in case 8K FFT is used and the SP pattern(Dx, Dy)=(16, 4), the value of MOD(NoC−1, Dx*Dy) is 0 for k=0, 2, 3; and32 for k=1, 3. Therefore, in case k=1, 3, the pilot pattern needs to bechanged to have a constant NoA.

FIG. 36 illustrates a case where the pilot pattern needs to be changedto support the constant NoA in case 8K FFT is used and the SP pattern(Dx, Dy)=(32, 4). In FIG. 36, in case 8K FFT is used and the SP pattern(Dx, Dy) (32, 4), the value of MOD(NoC−1, Dx*Dy) is 0 for k=0, 4; 32 fork=1; 64 for k=2; and 96 for k=3. Therefore, in case k=1, 2, 3, the pilotpattern needs to be changed to have a constant NoA.

FIG. 37 illustrates a case where the pilot pattern needs to be changedto support the constant NoA in case 16K FFT is used and the SP pattern(Dx, Dy)=(32, 4). In FIG. 37, in case 16K FFT is used and the SP pattern(Dx, Dy) (32, 4), the value of MOD(NoC−1, Dx*Dy) is 0 for k=0, 2, 4; and63 for k=1, 3. Therefore, in case k=1, 3, the pilot pattern needs to bechanged to have a constant NoA.

Change of the pilot pattern can be used to support a constant NoAaccording to the change of NoC by using a method for selectively usingone SP-bearing CP in case Dy=2 and 1 to 3 SP-bearing CPs in case Cy=4,which will be described again below.

In what follows, described will be a method for generating a common CPset and an additional CP set as a method for generating a CP patternaccording to an embodiment of the present invention. A common CP setrefers to a set of non-SP-bearing CPs not overlapping with the SP, andan additional CP set refers to a set of SP-bearing CPs overlapping withthe SP.

A broadcast system according to an embodiment of the present inventionsupports both 3 and 4 as a Dx basis value. Since the positions of thenon-SP-bearing CP and the SP-bearing CP have to be indexed withpredetermined values for all SP modes, the CP is designed with respectto the Dx basis value. Thus, design of the CP can be carried out by thefollowing two methods for the Dx basis 3 and 4.

i) A CP set is designed independently for the Dx basis 3 and 4, and a CPindex table is selected in association with selection of the SP mode.ii) One common CP set is selected by taking into account both of the Dxbasis 3 and 4 of the selected SP mode, and only one CP index table isdefined to be used independently of the SP mode selection.

Characteristics of the two methods above are as follows.

Since the method i) optimizes the position of a CP optimized for each Dxbasis case, it provides a better performance than the method ii). Sincethe method ii) has the same CP index independently of the SP mode, thereis no performance degradation due to discontinuity at the boundarieswhen sync tracking is required among the SP modes having different Dxbases. Also, the method ii) has the advantage that in case initialsynchronization is required since the Dx basis is not known beforehand,the receiver can anyhow use an existing CP set compared with the case ofusing two CP sets. Therefore, in what follows, described will be amethod for generating an SP pattern based on the method ii).

FIG. 38 illustrates a method for generating CP indices according to oneembodiment of the present invention.

FIG. 38 illustrates a method for generating a common CP set, andaccording to the method, CP sets corresponding to various FFT sizes canbe generated by using a reference CP set.

First of all, according to the present invention, a set ofnon-SP-bearing CPs not overlapping with an SP is generated by takinginto account both of the aforementioned SP modes of Dx=3 and Dx=4, wherethe CP set can be called a reference CP set. The reference CP set cancorrespond to the left half of the 32K FFT mode CP set. In other words,since the number of CPs in the 32K FFT mode is 180 when k=0, thereference CP set can include 90 CPs. The reference CP set is generatedto satisfy the condition that “CPs are positions to be distributedevenly and in random fashion over the predetermined spectrum”. Thereference CP set is extracted by taking into account variousperformances of a plurality of CP position patterns generated through aPN generator, which will be described later.

The CP set with respect to the 32K FFT mode (CP_32K) generates anadditional right-half CP set (CP_32K,R) by reversing and shifting thereference CP set (CP_32K,L) and adding the right-half CP set to thereference CP set. The reversing operation may be called a mirroringoperation, and the shifting operation may be called cycling shifting.The reversing and shifting operation may be regarded as the operation ofreducing indices of the reference CP set at the reference carrierpositions. The reference carrier position is determined with respect tothe shifting value, which may be called a reference index or a referenceindex value. Generation of the right-half CP set of 32 K mode (CP_32K,R) and the method for generating a CP set of 32K FFT mode using the CPset may be expressed by the equation below.

CP_32K,R=reference carrier index−CP_32K,L

CP_32K=[CP_32K,L,CP_32K,R]  [Equation 14]

A CP set for 16K FFT mode (CP_16) and a CP set for 8K FFT mode (CP_8)can be extracted respectively from the CP set for 32K FFT mode (CP_32).In this case, as shown in FIG. 38, the reference CP set is determined sothat extracted CPs can be placed at the same position in the frequencydomain.

According to the method, since the broadcast transmitter and thebroadcast receiver only have to store the CP set corresponding to thehalf of the CP indices used in the 32K mode, size of the required memorycan be reduced.

FIG. 39 illustrates a method for generating a CP set according to FFTsize according to an embodiment of the present invention.

A plurality of conditions should be met to determine a reference CP set.For example, i) the position of an SP pattern having the largest Dxvalue that can be supported for each FFT mode should be avoided, ii)generation of a 16K and 8K CP set should be derived from the CP set of32K FFT mode through a simple operation such as rounding, ceiling, orflooring, iii) continuity in absolute frequency for all FFT modes shouldbe satisfied.

These CP indices are chosen in such a way to avoid the position of theSP as in FIG. 39, and in particular, the CP indices are also chosen tobe positioned at the same position in the frequency domain for 16K and8K modes. Among the indices chosen, those distributed as evenly andrandomly as possible across the signal bandwidth are chosen to beincluded in the reference CP set.

As described above, if the CP set of 32K FFT mode (CP_32K) is generatedby using the reference CP set, the CP set of 16K mode (CP_16K) and theCP set of 8K mode (CP_8K) can be obtained by using the CP set of 32 kFFT mode (CP_32K) and the equations below. In particular, if thecondition for continuity in absolute frequency for all FFT modes isrelieved, the number 18 can be applied. To achieve better precision offrequency position, more accurate channel estimation based on the moreprecise frequency position, and frequency/time synchronization, thepresent invention uses the ceiling operation of Eq. 15; however,operation of Eqs. 16 to 19 may be used depending on the needs.

CP_16K=ceil((take every 2nd index of CP_32K)/2)

CP_18K=ceil((take every 4th index of CP_32K)/4)  [Equation 15]

Equation 15 represents generating a CP set of 16 K mode by applying theceiling operation on every second index of the CP set of 32K modedivided by two and generating a CP set of 8K mode by applying theceiling operation on every fourth index of the CP set of 32K modedivided by 4. The ceiling operation value represents the smallestinteger among those numbers larger than or equal to the target value.

CP_16K=floor((take every 2nd index of CP_32 K)/2)+1

CP_18K=floor((take every 4th index of CP_32K)/4)+1  [Equation 16]

Equation 16 represents generating a CP set of 16 K mode by applying theflooring operation on every second index of the CP set of 32K modedivided by two and generating a CP set of 8K mode by applying theflooring operation on every fourth index of the CP set of 32K modedivided by 4. The flooring operation value represents the largestinteger among those numbers smaller than or equal to the target value.

CP_16K=round((take every 2nd index of CP_32K)/2)

CP_18K=round((take every 4th index of CP_32K)/4+1)  [Equation 17]

CP_16K=round((take every 2nd index of CP_32K)/2)

CP_18K=round((take every 4th index of CP_32K)/4)+1  [Equation 18]

CP_16K=round((take every 2nd index of CP_32K)/2)

CP_18K=round((take every 4th index of CP_32K)/4)  [Equation 19]

In Eqs. 17 to 19, the round operation returns an integer closest to thetarget value.

The condition for continuity in absolute frequency for all FFT modesshould be satisfied in order to perform channel estimation moreaccurately even if the FFT size is changed. Since pilots are positionedat the same position even if the FFT size is changed, the broadcastreceiver can estimate the channel more accurately and compensate thetime/frequency offset by using the pilot positions of a preceding andfollowing signal. In other words, it can be more effective particularlyin such a case where FFT sizes are different from each other for eachsegment of a signal in one frame.

FIGS. 40 and 41 illustrate a method for generating a reference CP setand generating a CP pattern using the reference CP set according to oneembodiment of the present invention.

FIG. 40 illustrates common CP sets, each of which is a set of CPs notincluding an SP.

FIG. 40 illustrates a reference CP set generated by taking into accountthe aforementioned conditions (CP_ref); and a method for generating a CPset when the FFT size is 32 K (CP_32K), a CP set when the FFT size is16K (CP_16K) and a CP set when the FFT size is 8K (CP_8K)

In FIG. 40, CP_ref represents the reference CP set (CP_32K, L),including pilot indices corresponding to the first half of the 32K modeCP set (CP_32K). The 32K_mode CP set (CP_32K) is generated by using Eq.14, of which the reference carrier index is 27649. The 16K mode CP set(CP_16K) and the 8K mode CP set (CP_8K) are generated individually byusing Eq. 15.

FIG. 41 illustrates CP indices of 32K mode CP set, 16K mode CP set, and8K mode CP set generated by using the reference CP set of FIG. 40.

FIGS. 42 to 45 illustrate a method for generating a reference CP set andgenerating a CP pattern using the reference CP set according to anotherone embodiment of the present invention.

FIG. 42 illustrates common CP sets, each of which is a set of CPs notincluding an SP.

FIG. 42 illustrates a different reference CP set generated by takinginto account the aforementioned conditions (CP_32K, L or CP_ref); and amethod for generating a CP set when the FFT size is 32 K (CP_32K), a CPset when the FFT size is 16K (CP_16K), and a CP set when the FFT size is8K (CP_8K)

In FIG. 42, the reference CP set (CP_32K, L) includes pilot indicescorresponding to the first half of the 32K mode CP set (CP_32K). The 32Kmode CP set (CP_32K) is generated by using Eq. 14 (CP_32K, R=referenceindex value−CP_32K, L; and CP_32K=[CP_32K, L, CP_32K, R]), and thereference carrier index is 27648. The 16K mode CP set (CP_16K) and the8K mode CP set (CP_8K) are generated by using Eq. 15 (CP_16K=ceil ((takeevery 2nd index of CP32K)/2) and CP_16K=ceil (take every 2nd index ofCP32K)/4), respectively. In other words, the 16K FFT CP set (CP_16K) cancomprise the index values obtained by dividing the first, third, fifthindex, and so on of the 32K FFT CP set (CP_32K) by 2 and applying theceiling function to the division result, while the 8K FFT CP set (CP_8K)can comprise the index values obtained by dividing the first, fifth,ninth index, and so on of the 32K FFT CP set (CP_32K) by 4 and applyingthe ceiling function to the division result.

FIGS. 43 to 45 illustrate CP sets generated by using the reference CPset of FIG. 43, where FIG. 43 illustrates CP indices of 32K CP set, FIG.44 illustrates CP indices of 16K CP set, and FIG. 45 illustrates CPindices of 8K CP set.

FIGS. 46 to 51 illustrate performance and distribution of CP sets shownin FIGS. 42 to 45.

FIG. 46 illustrates an Average Mutual Information (AMI) plot showing aperformance test result with respect to the AWGN channel, FIG. 47illustrates an AMI plot showing a performance test result with respectto the 2-way Rayleigh channel, and FIG. 48 illustrates an AMI plotshowing a performance test result with respect to Tu-6 200 Hz channel.And FIG. 49 illustrates a relationship between the Average MutualInformation (AMI)/bit and distribution index for each channel. Theembodiments of FIGS. 42 to 45 correspond to the CP indices generated bytaking into account the performance in various channels as shown inFIGS. 46 to 51, compared with the embodiments of FIGS. 40 and 41.

FIG. 50 illustrates that indices of the 32K mode CP set (CP_32K), 16Kmode CP set (CP_16K), and 8K mode CP set (CP_8K) exhibit random and evendistribution performance.

FIG. 51 is a magnified view of a part of the CP sets of FIG. 50. In FIG.51, the 8K mode CPs are positioned at the same positions with the 16Kmode and 32K mode CPs; and illustrates that the 16K mode CPs are alsopositioned at the same positions with the 32K mode CPs. Therefore, itcan be understood from the descriptions above that performance ofchannel estimation and frequency synchronization can be improved.

FIG. 52 illustrates additional CP sets according to an embodiment of thepresent invention.

As described above, a CP set includes a common CP set and an additionalCP set; and the additional CP set required to retain a constant NoAaccording to an SP pattern and FFT size (mode) is inserted additionally.The additional CP set is an SP-bearing CP, where fewer than 3 CPs can beinserted if Dy is 4, and one or zero CP can be inserted if Dy is 2.

Since the number of carriers is reduced by a multiple of the controlunit value according as the flexible NoC is used as described withrespect to FIGS. 34 to 37, the additional CP set has to be changedaccording to the NoC to retain constant NoA. In FIG. 52, the additionalCP set changed in this sense is denoted by parentheses.

In the example of FIG. 52, the additional CP set is changed when the FFTmode is 16K and 8K and the SP mode is SP32-4; when the FFT mode is 8Kand the SP mode is SP32-2; and when the FFT mode is 8K and the SP modeis SP16-4. The pilot indices in parentheses may not be used if k cannotbe divided by 2, namely, in case k is an odd number (k mod 2=1 where k=1or 3) in Eq. 12. Each case will be described later.

First, in case the SP pattern is SP32-2 and the FFT mode is 8K, theadditional CP set can be changed. In other words, if k is an odd number(for example, k=1 or 3) in the case of flexible NoC, the SP-bearing CPof the CP index 1696 may not be used and the additional SP-bearing CPmay not be defined at all.

In case the SP pattern is SP16-4 and the FFT mode is 8K, the additionalCP set can be changed. In other words, if k is an odd number (forexample, k=1 or 3) in the case of flexible NoC, the CP of index 2912 andthe CP of index 5744 may not be used, but only the SP-bearing CP ofindex 1744 can be added.

In case the SP pattern is SP32-4 and the FFT mode is 16K, the additionalCP set can be changed. In other words, if k is an odd number (forexample, k=1 or 3) in the case of flexible NoC, the CP of index 5824 andthe CP of index 11488 may not be used, but only the SP-bearing CP ofindex 3488 can be added.

In case the SP pattern is SP32-4 and the FFT mode is 8K, the additionalCP set can be changed, and in this case the additional CP set can beinserted differently according to the k value. In other words, if k=1 inthe case of flexible NoC, all of the CP of index 1696, CP of index 2880,and CP of index 5728 may not be used nor may the additional CP set beinserted additionally. In case k=2, the CP of index 2880 and the CP ofindex 5728 may not be used, but only the SP-bearing CP of index 1697 canbe added. In case k=3, the CP of index 5728 may not be used, but theSP-bearing CP of index 1697 and the SP-bearing CP of index 2880 can beadded. And in case k=0 or k=4, the SP-bearing CPs of index 1696, index2880, and index 5728 can be added.

In this way, a CP set can be constructed so that a constant NoA can beretained even if bandwidth is masked out as the NoC is formed in aflexible manner.

FIG. 53 illustrates a method for positioning the index of an additionalCP set of FIG. 52.

As described above, in case Dy=2 and Dy=4, 1 and 3 SP-bearing CPs can beadded respectively. The SP-bearing CPs are defined at such positions tosatisfy the constant NoA, and among those positions, the SP-bearing CPsare inserted to where the CPs can be distributed more evenly andrandomly as in FIG. 53.

FIG. 54 illustrates a method for transmitting a broadcast signal ofanother broadcast signal transmitter according to an embodiment of thepresent invention.

As described above with respect to the broadcast signal transmitter andits operation, the broadcast signal transmitter can demultiplex inputstreams into at least one Data Pipe (DP), namely, Physical Layer Pipe(PLP) by using the input formatting module S54010. And the broadcastsignal transmitter can perform error correction processing or FECencoding on the data included in at least one DP (PLP) by using the BICMmodule S54020. The broadcast signal transmitter can generate a signalframe by mapping the data within the PLP by using the frame buildingmodule S54030. The broadcast signal transmitter can insert a preambleinto a transmission signal and perform OFDM modulation by using the OFDMgeneration module S54040. Insertion of a pilot by the broadcast signaltransmitter can be carried out by using the methods of FIG. 8 and FIGS.30 to 53.

The OFDM generation module further comprises a pilot signal insertionmodule and the performing OFDM modulation S54040 can further compriseinserting a pilot signal including CP and SP into the transmissionsignal. The CP is inserted into every symbol of the signal frame, andthe position of and the number for the CP may be determined based on theFFT size/mode. However, the CP may not be inserted into the preamblesymbol part or the bootstrap symbol part.

The broadcast signal transmitter can generate a signal frame by usingthe frame building module, and in this case, configure the NoC to beflexible, and generate a signal frame according to the configured NoC.In other words, the number of carriers included in the signal frame canbe reduced by the unit of multiplication of the control unit value and apredetermined coefficient from the number of the maximum carriers, wherethe control unit value can correspond to the predetermined number ofcarriers based on the FFT size. At this time, the control unit value cancorrespond to 96 in case the FFT size is 8, 192 in case the FFT size is16, and 384 in case the FFT size is 32. The number of NoC may betransmitted or received being included in the preamble as signalinginformation. For example, the information representing the coefficientof NoC reduction, k, may be transmitted or received being included inthe preamble.

CPs can include a common CP set and an additional CP set. The CPsbelonging to a common CP set can be disposed at the positions notoverlapping with the SP, while the CPs of an additional CP set can bedisposed at the positions overlapping with the SP.

The common CP set can be determined as in FIGS. 31 to 33 and FIGS. 38 to45. In other words, the reference CP set corresponding to the first halfof the 32K FFT mode CP set is stored in the broadcast signaltransmitter, and by using the reference CP set, the broadcast signaltransmitter can generate and insert 32K, 16K, and 8K mode CP setsrespectively as described. In other words, the 32K mode CP set can begenerated by adding a right-end CP set generated by reversing andshifting the reference CP into the reference CP set. The 16K mode CP setcan be generated by extracting CPs of every second index from among theCPs belonging to the 32K mode CP set, while the 8K mode CP set can begenerated by extracting CPs of every fourth index from among the CPsbelonging to the 32K mode CP set.

The additional CP set can be inserted into a broadcast signal as shownin FIG. 52. In other words, in case NoC is reduced, a specific FFT sizeand an additional CP set with respect to a specific SP pattern can beadded as different CP indices according to predetermined coefficients.

FIG. 55 illustrates a method for receiving a broadcast signal accordingto one

As described above with respect to the broadcast signal receiver and itsoperation, the broadcast signal receiver can perform signal detectionand OFDM demodulation on a received broadcast signal by using thesynchronization/demodulation module S55010. The broadcast receiver canextract service data by parsing a signal frame of a received broadcastsignal by using the frame parsing module S55020. The broadcast signalreceiver can convert service data extracted from the received broadcastsignal into the bit domain and perform deinterleaving on the convertedservice data by using the demapping and decoding module S55030. And thebroadcast signal receiver can output service data processed by theoutput processing module into a data stream S55040.

The synchronization/demodulation module further comprises a pilot signaldetecting module, and the performing OFDM demodulation S55010 canfurther comprise detecting a pilot signal such as the CP and SP from atransmission signal. The CP is inserted into every symbol of the signalframe, and the position of and the number for the CP may be determinedbased on the FFT size/mode.

The frame parsing module of the broadcast signal receiver can parse thesignal frame according to the NoC, and information of the NoC intendedfor the parsing may be transmitted or received being included in thepreamble as signaling information. For example, the informationrepresenting the coefficient of NoC reduction, k, may be transmitted orreceived being included in the preamble.

The synchronization/demodulation module of the broadcast signal receivercan further comprise the time/frequency synchronization module and canperform time/frequency synchronization by using pilot signals detectedby the pilot detecting module. Since the pilot signals of theaforementioned received signal have the structure/characteristics of thepilot signal inserted by the broadcast signal transmitter describedabove, the characteristics about the pilot signals of the transmittercan be applied the same to the received broadcast signal. In otherwords, descriptions of the signal structure, pilot structure, and so onrelated to FIG. 54 can all be applied to the broadcast signal receivedby the broadcast receiver of FIG. 55.

The broadcast signal receiver can perform time/frequency synchronizationby comparing the pilot signal detected by the time/frequencysynchronization module with the predetermined pilot signal position. Inthis case, the broadcast signal receiver may perform time/frequencysynchronization by obtaining the position of the common CP set and theadditional CP set as described with respect to the transmitter andcomparing the obtained pilot signals with the pilot signals detectedfrom a received signal.

In this document, the DP refers to as the Physical Layer Pipe (PLP), andPLS1 information may be called Layer 1 (L1) static information, and PLS2information may be called L1 dynamic information.

It should be clearly understood by those skilled in the art that variousmodifications and changes of the present invention can be made withoutleaving the technical principles and scope of the present invention.Therefore, it should be understood that the present invention includesthe modifications and changes of the present invention supported by theappended claims and their equivalents.

This document describes all of the apparatus and methods related to thepresent invention, and descriptions thereof can be applied in acomplementary manner.

What is claimed is:
 1. A broadcast signal transmitter comprising: aninput formatting module configured to de-multiplex an input stream intoat least one PLP (Physical Layer Pipe); a BICM (Bit Interleaved CodedModulation) module configured to perform error correction processing onthe data of the least one PLP; a frame building module configured togenerate a signal frame including the at least one PLP; a waveformgenerating module configured to generate the broadcast signal byinserting a preamble into the signal frame and performing OFDMmodulation, wherein the waveform generating module further comprises apilot insertion module configured to insert pilots including CPs(Continual Pilots) and SPs (Scattered Pilots) to the broadcast signaland wherein the CPs are inserted in every symbol of the signal frame anda number of the CPs is determined based on FFT (Fast Fourier Transform)size.
 2. The broadcast signal transmitter of claim 1, wherein a numberof carriers included in the signal frame is reduced by a unit from amaximum number of carriers, the unit being obtained by multiplying acontrol unit value by a reducing coefficient, and the control unit valuecorresponds to a predetermined number of carriers which are determinedbased on the FFT size.
 3. The broadcast signal transmitter of claim 2,wherein the control unit value corresponds to 96 when the FFT size is 8,192 when the FFT size is 16 and 384 when the FFT size is
 32. 4. Thebroadcast signal transmitter of claim 1, wherein the CPs include acommon CP set and an additional CP set.
 5. The broadcast signaltransmitter of claim 4, wherein the common CP set includes a first CPset for 32K FFT mode, a second CP set for 16K FFT mode, and a third CPset for 8K FFT mode; and the first CP set, the second CP set, and thethird CP set are generated by using a predetermined first reference CPset.
 6. The broadcast signal transmitter of claim 5, wherein the firstCP set is generated by adding a second reference CP set to the firstreference CP set and the second reference CP set is generated byreversing and shifting the first reference CP set.
 7. The broadcastsignal transmitter of claim 6, wherein the second CP set is generated byderiving CPs of every second index from CPs included in the first CPset.
 8. The broadcast signal transmitter of claim 6, wherein the thirdCP set is generated by deriving CPs of every fourth index from CPsincluded in the first CP set.
 9. The broadcast signal transmitter ofclaim 4, wherein the additional CP set is added at carrier location ofSP for ensuring a constant number of data carriers in every data symbolof the signal frame and the additional CP set depends on SP pattern andthe FFT size.
 10. The broadcast signal transmitter of claim 9, whereinthe number of carriers included in the signal frame is reduced by a unitfrom a maximum number of carriers, the unit being obtained bymultiplying a control unit value by a reducing coefficient, and thecontrol unit value corresponds to a predetermined number of carrierswhich are determined based on the FFT size, wherein the additional CPset for a specific SP pattern and a specific FFT size is addeddifferently according to the reducing coefficient.
 11. A method fortransmitting a broadcast signal, comprising: demultiplexing an inputstream into at least one PLP (Physical Layer Pipe); performing errorcorrection processing on the data of the least one PLP; generating asignal frame including the at least one PLP; and generating a broadcastsignal by inserting a preamble into the signal frame and performing OFDMmodulation, wherein the generating a signal frame further comprisesinserting pilots including CPs (Continual Pilots) and SPs (ScatteredPilots) to the broadcast signal and the CPs are inserted in every symbolof the signal frame and a number of the CPs is determined based on FFT(Fast Fourier Transform) size.
 12. The method of claim 11, wherein anumber of carriers included in the signal frame is reduced by a unitfrom a maximum number of carriers, the unit being obtained bymultiplying a control unit value by a reducing coefficient, and thecontrol unit value corresponds to the predetermined number of carrierswhich are determined based on the FFT size.
 13. The method of claim 12,wherein the control unit value corresponds to 96 when the FFT size is 8,192 when the FFT size is 16 and 384 when the FFT size is
 32. 14. Themethod of claim 11, wherein the CPs include a common CP set and anadditional CP set.
 15. The method of claim 14, wherein the common CP setincludes a first CP set for 32K FFT mode, a second CP set for 16K FFTmode, and a third CP set for 8K FFT mode; and the first CP set, thesecond CP set, and the third CP set are generated by using apredetermined first reference CP set.
 16. The method of claim 15,wherein the first CP set is generated by adding a second reference CPset to the first reference CP set and the second reference CP set isgenerated by reversing and shifting the first reference CP set.
 17. Themethod of claim 16, wherein the second CP set is generated by derivingCPs of every second index from CPs included in the first CP set.
 18. Themethod of claim 16, wherein the third CP set is generated by derivingCPs of every fourth index from CPs included in the first CP set.
 19. Themethod of claim 14, wherein the additional CP set is added at carrierlocation of SP for ensuring a constant number of data carriers in everydata symbol of the signal frame and the additional CP set depends on SPpattern and the FFT size.
 20. The method of claim 19, wherein the numberof carriers included in the signal frame is reduced by a unit from amaximum number of carriers, the unit being obtained by multiplying acontrol unit value by a reducing coefficient, and the control unit valuecorresponds to a predetermined number of carriers which are determinedbased on the FFT size, wherein the additional CP set for a specific SPpattern and a specific FFT size is added differently according to thereducing coefficient.